lemmit.online is a controversial lemmy server since its sole purpose is to run a bot that mirrors reddit posts to lemmy. Previous discussion 3 years ago about whether to block it: https://lemmy.ca/post/1380644
Currently it is blocked from lemmy.ca and I would like to unblock it to ease weaning off reddit gradually. If I can use lemmy.ca as my main site with links off to reddit on occassion I don’t need to use reddit anymore to browse but just drop in for a specific post of interest.
The main complaint is it can fill up the all category with high volume of low interaction posts. This can be dealt with on a per user basis by blocking either the lemmit.online instance or blocking the bot@lemmit.online user.
Looking at the top 10 lemmy instances on https://fedidb.com/software/lemmy here’s who allows or blocks the lemmit.online instance:
lemmy.world ✅
lemmy.ml ✅
sh.itjust.works ✅
lemmy.dbzer0.com ✅
lemmy.ca ❌
programming.dev ✅
lemmy.zip ✅
lemmy.blahaj.zone ❓
ttrpg.network ✅
lemmy.one ✅

Lemmit.online has ended with the shutdown of old reddit - https://lemmit.online/post/8716662?scrollToComments=true
I had created a new user on lemmy.dbzer0.com and subscribed to some bot communities mirrored from reddit via lemmit.online before it shutdown. The experience was underwhelming but it did lessen my need to use reddit as a social media app for discovery.