I have no desire to see facebook in the fediverse, but that's not really gentrification, it's more like Walmart. (Anti-competitive corporate monopoly suppressing competition and forcing everyone to serve their bottom line)

Gentrification refers to the displacement of poor and working class people, and especially people of color, by affluent people, especially white. That's not the specific dynamic here, in no small part because Mastodon has been self-gentrifying[^1] aggressively from the beginning. (It is jokingly referred to as the HOA of the internet)

[^1]: Through white techies being constantly obnoxious to POC who have the temerity to try to join the fediverse, the particular culture of content warning policing, and lack of discoverability making it hard to form community. Note: there's no reason to think facebook would improve any of this.