I have seen that lemmy.world apparently has a very poor reputation among other instances.

It’s the largest by far, with five times the monthly active population of #2. One of the main things people want out of federated systems is decentralization, and having one huge dominant server goes against that goal.

I should note .world wasn’t the biggest when I signed up. I picked it because mastodon.world was a known quantity, which led me to believe the same team would run a stable server.