Well, there's a self-proclaimed Left which, though probably having started out with good intentions, is all about "lets classify people on visible things they were born with and then presume things about them purelly on their "classification" and treat them differently".
If this sounds strangelly like the far-right thinking that's because it is kinda derivative: the same architecture of deeming individuals as worthy/unworthy likely-good/likely-bad because they were born with certain characteristics as the far-right is used, and then the categories are swapped and the whole thing is called "being progressive" as if it was only unfair to judge and treat people because of their genetic makeup if done in one direction but not in a different one.
Then there is the tankie Left, which also started with good intentions but seem to have confuse the recipe-book of slogans and the Party über alles discipline invented in the late 19th century and early 20th century by middle class intellectuals to inspired the near-illiterate masses of the time to create an utopian leftwing world (which didn't work) with the actual thinking Principles and Intentions from which the rules were made. Because these people follow the recipes without examining the against the principles and ideals and in contexts which are very different of the ones for which those rules were created, you went up with ridiculous ideas directly opposed to "the greatest good for the greatest number" principle like supporting Putin's invasion.
The followers of such "Lefts" hate it when their faith-like beliefs are examined against the actual Principles of Equality and "the greatest good for the greatest numbers" and found often to be directly opposing them, just like when you grab some religious book or other and point out the inconsistencies in it: there is no greater hate than that of the faithfull who sees the basis of their Identity be examined under the cruel light of logic and found to be mainly bollocks.
Or in other words, I think the Left here is a lot more the product of thinking things through and concluding that it would be a lot better to live in a World with less poverty, more equality and were a few did not amass more power than whole countries thanks to their wealth, and continuing to actually continue to think things through when face with slogans from the tribalist flag waving slogan parroting and social-circle-jerk groups which call themselves "Left" and which are the leftovers from Marxism in the XXI Century and the Neoliberal-inspired "in the greed is good context, lets pursue personal-upside maximization as an 'Identity' group instead of individually so that we can claim we're lefties".
PS: If it sounds I'm raging against the Left here, that just because I find the pettyness and self-serving sociopathy of the modern Right to be self-evident. I actually don't think you can be a true leftwinger genuinelly fighting for the greater good if you just blindly follow slogans and tribes. Funilly enough it also means I can actually respect a genuine old-style conservative, even whilst wholly disagreeing with him or her.
You need to be a leftie-in-name-only tribalist to confuse equal-opportunity skepticism with being on "the other side" - the conservatives, those people well known for questioning the way things are...
Then again, anybody who has reduced the entirety of political choices in society to a mere two sides as you hinted you have in your post, really hasn't though it through (there being billions of humans there is an almost infinite number of choices) and instead has firmly engaged with the whole thing in an us-vs-them tribalism devoid of logic.
In such a simplistic take on politics those questioning the beliefs you hold (in very much the same way as religious people hold theirs) couldn't possibly be questioning all ideas with Logic and Analytics to try and find the best way to increase the greatest good for the greatest number, but instead "must be from the other side".
This sounds like a straw man argument. The lefties I know are analytical and critical to a fault; unlike the righties they don't blindly wave the party flag, and that criticism reduces their support of party policies and presents itself as a lack of unity.
Being a member of a leftwing party in my own country, I can tell you that most members aren't analytical and critical when it comes to words uttered by celebrities "from their side".
In fact that was exactly my great dissapointment with that party as I became more and more familiar with it and the way it works: having come in thinking as you seem to do and expecting to find a Thinking Left, I ended up finding yet another bunch of mindless parrots who even lack self-awareness (I was pretty shocked in a National Party Conference when maybe 9 in 10 of party member interventions were of the "we the <insert groups that person belongs to> need/want/should-have ...", or in other words Personal Greed disguised as "for the group", the kind of shit that is rotting from the inside the genuine fight for Equality).
There are many "lefts" in the Left and a lot of them either interiorized greed as ok and practice an "as long as it helps me and doesn't affect my priviledges" type of being "left" (lots of high middle class Feminist around who strangelly focus entirelly or almost so on the "oppression" of high middle class women whose income is above 90% of people, rather than on that of, say, working class cleaning ladies who get up at 5 AM every day to go clean toilets for minimum wage), people so beholden to an old script that they lost sight of the principles why and from were that script was born, and people whose relation to the leftwing is akin to their relation with a sports club: of the heart, unthinking, unchallenging and always applauding whatever the club's stars say - perfect useful idiots being fed pap by people in leadership positions who either are manipulators rather than leftwing or are profoundly incompetent, with no vision and no strategy, hence are totally unable to advance leftwing principles (quite the contrary, judging by the way politics is going towards the far-right nowadays).
We do need more Genuinelly Thinking Left, not people consciously or unconsciously accepting accepting the "greed is good" of neolibs, or flag waving parrots with not even the awareness of how lost their party is without an actual vision or strategy and always reacting moment by moment to political events (making them oh-so-easy to manipulate by the mainstream political parties).
I am pretty fortunate to live in a quite progressive city in a fairly progressive state. I'm sure some of that goes on here as well, but the people I surround myself with seem to be genuinely interested in the greater good.
Well, I was born in Portugal and lived there until my 20s, at a time when the country was profoundly backwards in social issues, and then became an immigrant in The Netherlands, which I was for almost a decade during my young adult years, so I ended up wholehearthedly adopting the dutch version of Tolerance.
Now, remember that The Netherlands was maybe the first country to, for example, legalized gay marriage (in fact some of my colleagues there were British "refugees" who had move there so that they could get married with their partners) and even for a while had as leader of their far-right party (I kid you not!) an openly gay guy, and this kind of thing applies to a lot of other areas: for example, 20 years ago they already had 18% of "housemen" - stay at home fathers - and their tolerance on drug consumption is well known.
And their whole Tolerance practice is based on "it's all normal", "we're really all the same in what matters" and "it's not up to me to pass judgment on others", a view were for example discrimination on sexual orientation or religion is as ridiculous as descrimination on eye color or hair color: only a nutter would treat people differently because of any such things.
So for me the present day Anglo-Saxon format of Identity Politics were people are still classified on who they love or the genes they were born with and then measures are proposed and judgments made based on those group-membership classifications, is actually not progressive at all but rather regressive, and not just by years but by decades - it's like going back into some half-way between that Portugal of 3 decades ago (fortunatelly a lot better now) and The Netherlands.
I absolutelly can understand how in an environment where there is massive descrimination people of those groups discriminated against have to get together in order to fight against it (after all, "there is strength in numbers"), correct the injustices that have been done and change the system were such injustices are repeatedly done impunity (sometimes by the very State which should protect all citizens).
However the objective should be to, as such systemic injustices are eliminated, eventually end up with the dutch mindset (we're all the same, this is all normal, who am I to judge others) in the minds of everybody, and that's not at all possible if you keep on classifying people and effectivelly saying "these people are different", "this characteristic people have been discriminated by is extra important" (rather than normal), and practice "we should judge others", because you really can't have a natural fair and equal treatment on something if keep on dividing people on those things and keep emphasising those human characteristics as huge differences, and without fair and equal treatment becoming natural in the minds of most people, the fight will never be over and you'll constanty have pushback.
As I said, the intentions are good, but the methods are not and they are way too easy to subvert by those who care only about their personal upsides, even those on completelly opposite sides of the political spectrum who want to manipulate the masses via induced rage.
Then there is the tankie Left, which also started with good intentions but seem to have confuse the recipe-book of slogans and the Party über alles discipline invented in the late 19th century and early 20th century by middle class intellectuals to inspired the near-illiterate masses of the time to create an utopian leftwing world (which didn’t work) with the actual thinking Principles and Intentions from which the rules were made.
The "tankies" are absolutely not utopian. There was a great big schism about this very question more than a century ago, with Marxists roundly rejecting the utopianism of the libertarian socialists (Anarchists). Socialism: Utopian and Scientific by Engels is a good starting point.
Look, as I said in another post I am a member of a leftwing party in my homecountry, and that party has two big strains inside, which are pretty much the older generation (people in their late 60s+) most of which tend to be old style socialist/communist (though not fans of the local Communist Party, who they see as self-serving and with a deep authoritarian strain) and a newer generation in their 30s, sons and daughters of the high middle class, who don't really have a concrete ideology and make the politics up as they go, with not exactly great competence.
About a decade ago the old generation very purposefully made way for the new one, hence why that 2nd strain is so "narrow in their age range and social origins" (and quite blind to their own ignorance about how the other 95% or so of the population trully live and think).
Anyways, all of this to say that when the Russian Invasion of Ukraine started, I actually argued with one of those old guys, whose kneejerk reaction was to defend Russia (because in his worldview "Russia good, US bad"), and I convinced him to change his mind by pointing out that there was but one aggressor and one victim in this War and how it was entirelly consistent to be against the actions of Russia here as it was to be against the actions of the US in the second Iraq War as both were agressors killing people who did no harm to them, and further it was entirelly consistent with in life in general side with the victims against the aggressors.
If I understand the definition correctly, a "tankie" is what this guy was in his kneejerk pro-Russia reaction, yet I did manage to convince him to change his mind and did so with an entirelly humanist argument of siding with the victims, so I would say that his heart was in the right place.
More in general, my judgement of the old-school lefties I've been in contact with mainly through being in this party is that their intentions are good but they're often stuck in a slogan-heavy view of things which is severely outdated and rigid and which they learned in their early adulthood, often resulting in things like this kind of kneejerk defense of present day Russia because of what a very different Russia meant to them half a century ago, but as I described, it's still possible for their view to change when somebody gently and with some good examples points out that they're "sidding with the guys harming others" in their unthinking "taking a side" reaction.