You might look on MeanwhileOnGrad. Many of the posts criticize .ml specifically.

It is the oldest instance, so many people join it, even if it is no longer the most popular. People complain about the general userbase for having a noticeable pro-Russia bias, but most of the criticism I see is directed at the admins specifically. They have this same bias and aggressively censor people with it. Other admins may enforce strict rules for the instance they envision of course but .ml is also noticeably not open about this. Much of the removed content is censored with the justification of “Rule 1” or similar, but as far as I’m aware these rules don’t exist or at least are hidden from everyone expected to comply with them.

Edit: Forgot to mention, some people also complain that a portion of donations towards Lemmy’s development goes to paying for .ml server costs. One of them also had a controversial take on trans rights I think, but I don’t remember the details. At least one of the admins is fairly active and argumentative as well. When the admins are involved in this sort of drama it reflects poorly on the instance as a whole.