It takes nearly as long to decrapify a new Firefox install as it does to compile Librewolf.
Install uBlock.
Tell Firefox that you don't want to sync at the moment.
Disable "sponsored" stories. AKA, listicles designed to draw in idiots who want to see which 8 child actors from the 90s turned out to be the tallest. Alarmingly close to the tacky crap that you might see on a fresh Windows install.
Tell Firefox that you don't want to sync at the moment.
Now disable Pocket. Remembering to go into about:config to really disable it
Disable telemetry.
Tell Firefox that you don't want to sync at the moment.
Remove Amazon, Bing, et al. from the search engine list.
Remove "suggested" and "sponsored" autocomplete.
Tell Firefox that you don't want to sync at the moment.
Remind yourself that, despite this crap, Firefox is still a better browser than any Chromium knockoff.
Sync between mobile and Firefox is good though. Sadly I use Samsung Internet on Android because I think it's better, but when I used Firefox on both it was really good. I can still use KDE Connect to send the link to my clipboard, but it doesn't always connect (after a reboot) automatically.
Samsung internet is chromium and often out of date. On Android, use Fennec or Mull (both firefox based, mull is the best security*/privacy android browser)
It's not a bad thing that Firefox is doing little things to attract a broader audience, luckily you don't set it up very often and sync is there to use.
except it is like making it so things can just download without asking so you can go to a webpage and it just downloads stuff automatically which is really insecure but hey chrome does it that way so mozilla just oh so obviously has to copy them yeah you can fix it but that should in no way be the default
Sometimes this doesn't work though. I use Firefox at work, but I'm required to use Google Drive, and any pdf from Drive will automatically download to my default download location without prompting me. This may not be Mozilla's fault, but it's shitty that any site can just choose to ignore my preferences.
I have a similar problem on Android with forcing pinch to zoom. Sites can and do use code to forcibly resist this accessibility setting. Like, a lot of sites.
What about Palemoon? Or epiphany which is pretty decent if you enable extensions support via gsettings and use /etc/hosts for blocking ads for better performance?