well .ml is special, most probaboy don’t have a problem there but if you do you really do (ask me why the anime community on lemmy.ml is practically dead)

.world is just suffering from success, they regularly have federation troubles with other instances because they are by far the largest one and hence run into scaling troubles. Other than that it’s the most reddit like moderation wise also due to being so big. It’s courtesy to steer people away from .world simply to prevent the scaling problems from getting worse