Depends on the community. Some subreddits I used to go to migrated off the platform or closed down entirely, but many others just reopened with new staff and proceeded as usual. Not sure if activity was affected sitewide, though it feels a bit more quiet than it used to for me.
I've seen this happening for the city/state subreddits. Maybe the regulars stopped posting, because now it just reads like a Facebook group, constant fear mongering.
iirc there was a report in the Verge that overall content quality has fallen. r/all has mostly short trending tiktok video, earlier it used to be niche interesting topic, you wouldn't find anywhere else.
I started using tildes.net which is invite only interesting community.
