I made a Lemmy instance with a custom algorithm that keeps only the top 20% most unique (=interesting?) posts. It does this by calculating a similarity score between every post on my instance and all posts that came before it. The top 80% of posts with the highest self-similarity get removed instantly.
The idea would be that this allows me to cut through the noise that's running through the communities, similar to how xkcd-signal attempted to do 20 years ago.
The instance is mostly meant for reading, not posting. So it has a very open federation policy (for now).
If anything, this is experimental. So please let me know what you think! You can see the type of stuff that gets removed in the modlog (https://lemmy.coffee/modlog).
PieFed places an icon next to the username to help highlight such aspects of a person's account. The one for "new account, less than 2 weeks old" is very useful. Others need tweaking such as "potential unregistered bot that posts far more often than comments", and "contentious user with far more downvotes than upvotes". I find it useful not to block people but to simply scroll past or to tailor my response to knowing that info.
In addition to PieFed, there are some Lemmy apps that will do this too, although I am not sure which ones (perhaps check out Sync and Connect) - the trick here is ofc to auto apply it to all accounts as you read through your feed.