This isn't a problem of Lemmy itself in terms of the software, so I'm not sure it qualifies... But, I find that Lemmy still has the same problem of Reddit where if you say something that the majority of users disagree with, prepare to be torn apart in the comments. And I do not just mean by getting corrected on something you said being factually incorrect, I mean more of a "your opinion is wrong because..."
For example, any discussion revolving around Linux (and let me just prepend this by saying I am a Linux user), if you happen to prefer using Windows be prepared to be told all of the reasons why you have to use Linux instead. And that's usually tame compared to what I've seen on other subjects.
Obviously there are cases where yeah, you absolutely deserve to be torn a new one in the extreme cases when someone is actually being truly vile, such as trying to advocate for the harm of someone/a group of people - but the "extremes" are not what I'm really referring to here.
I've blocked a lot of users that while I've had no interaction with them, I see how they are clearly engaging in, let's just say, bad faith with others.
In terms of software-specific issues, I can't say that I really have had a lot of problems with Lemmy itself as of recently. As an instance owner, I used to have a lot of weird (what seemingly appeared to be, at least) random federation issues, but I haven't seen any federation problems in a while now. Though just today I swear I submitted a comment somewhere, and its just poof not there - not even locally, but I'm chalking that one up to something I've done (whether a misclick, or I'm just hallucinating as badly as an LLM) rather than an actual issue.
Does Chrome's run locally on the machine, or does it ferry it over to Google Translate?
Firefox's is done locally, it is not cloud based.