It’s pretty obvious that when a server goes offline the total number of posts will go down, but it’s not a helpful metric. Comparing the posts per day, rather than total number of posts on different days, would give a better idea of the effect.

I was registered on Lemm.ee. Now I’m registered on piefed.social. So, technically not Lemmy anymore. I do suspect a lot us moved to piefed. That was the general buzz. I genuinely don’t know if the posts and comments of Piefed don’t track on Lemmy. I’m sure the ones amongst piefed users in piefed instances don’t though. That alone could justify a substantial part of that drop. But I’m still here interacting with Lemmy.