Don’t underestimate how much resistance to change stops people from looking beyond the status quo. Moving away from Reddit is a clear example. I suspect a lot of lurkers from Reddit are actually from the category of Late Majority or Laggards
https://www.betterup.com/blog/resistance-to-change
https://www.liveabout.com/what-is-resistance-to-change-1918240
https://ondigitalmarketing.com/learn/odm/foundations/5-customer-segments-technology-adoption/
There a new influx in the user migration as well, as some subreddits started pinning lemmy and kbin.social instances on their subs. Also if you go on protest subreddits (such as ModCoord and Save3rdPartyApps) almost every post has a thread/comment redirecting people to the fediverse.