lemmy.world is the largest Lemmy instance by far and is causing growing concern that it's causing the Lemmy-verse to become too centralized and strangling out smaller instances either intentionally (if .world defed's from your instance you immediately start losing out on a ton of content/traffic) or unintentionally (people just post there by default leaving little content for other instances)
So now there's ongoing efforts to try to balance things out a bit
Lack of updates on LW. At this moment, LW users still can't delete media they uploaded. That was a big deal in March 2024: https://tech.michaelaltfield.net/2024/03/04/lemmy-fediverse-gdpr/. Since then, Lemmy allows it since 0.19.4, but LW still runs 0.19.3 (there are plans to update, but at the moment we're speaking, it's still not the case)
Smaller instances can have issues to keep up with LW due to its size: https://lemm.ee/post/28755787 . Again, those issues were fixed in 0.19.6, but LW is still on 0.19.3.
The moral panic about tankies is a waste of time that distracts from focusing on the elites destroying our planet and emiserating the lives of disadvantaged communities.