I'm not sure what else will be able to cause a spike again. Reddits behavior over the past month is pretty much as terrible as it can get. If people aren't moving to Lemmy anymore, it's going to take something apocalyptic to cause Lemmys usercount to grow again.

Lemmy isn't overloaded. Lemmy.world and Lemmy.ml are.

People need to move to other instances. Lemmy was never designed to have main central instances. There are supposed to be many smaller and more specific ones and people choose the ones that fit their usage.