Lemmy is not immune to trolls, bad fait actors or propaganda - in fact, despite how bad reddit is, a lot of Lemmy instances are worse
I'm done, I've been banned for expressing a different opinion (without insulting or personally attacking anyone), I've been accused of evading a ban with multiple accounts (this is my only account I've ever had on any lemmy instance), I've had people selectively ignore my comments and accuse me of things which I never said, and I've had people ignore valid criticisms and keep attacking me.
Reddit has many issues with trolls, one-sided discussion, and just general bullshit, but many Lemmy instances are way worse. The newfound freedom of Lemmy has attracted many extremists, from both sides, and many of them are moderators, who are more than happy to remove any contrarian opinions. This results in discussions being echo chambers
Click on your username up top, then Settings.
Go to the Blocks tab.
Block community/instance/user you wish.
I checked midwest.social, and it is running 0.19+, so it can do that. For anyone else reading this, it won't work until your instance is on 0.19 or later. Scroll to the the very bottom of your lemmy page to see what version your instance is running.