[insightcheck]

This is just a guess, but probably various subreddits and Discord servers. It's probably not the same because the platforms are very different, but people will find new platforms even if the conversation changes due to different forum/messaging UI designs.

[dumpsterlid]

"and Discord servers"

vomits in my mouth a bit

[insightcheck]

Could be more different. In less tech-focused communities, the migration that follows a forum closure goes to Facebook groups instead of subreddits, and Slack channels instead of Discord.