Obviously a few years ago, the API changes caused the reddit community mods to strike, and caused a mass-blackout of most reddit core communities. Eventually Reddit removed a handful of mod teams on some notable subreddits and caused the rest to chicken-out. But it did birth the Fediverse properly.
I suspect Reddit will make another step at some point which causes another comparable exodus. This time, if they do, the Fediverse is far better developed to handle it. What do you imagine it might be?
I don’t think there’s going to be another “mass exodus” again. There are people who said that they were going to leave reddit and actually did. Then there are those who said the same but didn’t. Those people will never leave until the site shuts down or they’re dead. I mean there’s not much more Reddit can do to drive people away unless they go on a massive subreddit ban wave on things that shouldn’t be banned. or they introduce a subscription plan where you have to pay to “unlock” the site and can view as much content as you want. Even then people WILL pay for that.
But even with the plethora of bots, reposts, karma farming, and power tripping mods people still stick around.