That message on subredditstats is more recent than the sharp drop; the drop appeared during and immediately after the protest, and the users didn't come back. The policy change took effect shortly after, and subredditstats only recently added that message to their pages (it wasn't there ~week ago).
It also passes the sniff test. Pick any of the largest subreddits from the list and look at its front page. r/funny, with 54m "readers", has multiple posts on its front page right now with less than a dozen comments. r/news has more activity on its posts, but still far, far less than 2019.
It's not like there's a thriving community on Reddit that makes subredditstats' numbers look wildly wrong.
In 2022, The top show has 21,000 votes and 4,000 comments. 2 others have more than 1,000 comments, 4 have more than 4,000 votes, and 13 have more than 300 comments, including the 16th most popular show.
In 2023, the top show has 4,231 votes and 700 comments. 1 other show have more than 4,000 votes, 1 has more than 1,000 comments, and 8 are above 300 comments.
It also passes the sniff test. Pick any of the largest subreddits from the list and look at its front page. r/funny, with 54m "readers", has multiple posts on its front page right now with less than a dozen comments. r/news has more activity on its posts, but still far, far less than 2019.
It's not like there's a thriving community on Reddit that makes subredditstats' numbers look wildly wrong.