There was a previous post on that community about Burggit shutting down, but because it just linked to the announcement without explaining any of the details it didn't get a lot of attention or generate much discussion, with most of the comments simply consisting of "loli bad".
So I made a post yesterday specifically focusing on the grievances with the Lemmy software that the Burggit admins brought up, and there were some interesting comments, with one of the Lemmy devs responding as well.
To summarize: Most of the instance admins who commented seem to agree that the Lemmy software is lacking and devs are rather slow with updates, others contend that coding moderation tools is difficult and boring, some recommend addons/tools that have been created by other devs to help with Lemmy, and some people say they've had few problems with their instances, or found easy workarounds to the known problems. Nutomic, one of the Lemmy devs, also says that many of the issues that have been brought up have either been solved or improved in more recent versions of Lemmy. Some users also discuss what's reasonable to expect from the small dev team considering the current funding that they receive, and there's a bit of bickering in there too.
People are still commenting on the post so I definitely recommend checking out the full thread to see how the discussion evolves.
Never heard of fediseer before, but their censured list is a great place to find new instances!