@kumicotaIts not about either of those actually
tl;dr Gab - which is a scam social network for facebook boomers, is forking mastodon so they can use existing fedi apps (gab apps are banned from app stores) and their users can self host the gab fork and create a federated gab that might (but might not) also be compatible with mastodon & the rest of the fedi (so we can see them)
To protect their apps from getting kicked off the App Store and Google Play popular fedi apps Tusky and Fedilab decided to implement code in their apps that makes it so gab domains can't log in (their fork doesn't exist yet, we don't even know what the url will be)
there's nothing wrong with this protection measure to stay on app stores imo, but its a drastic measure. I predicted weeks ago that people like in this screenshot I posted would come out and say they should also block servers they just don't like. Sure they mention FSE by name but they really mean instances like pl.smuglo.li, shitposter.club, niu.moe, and any other instance that doesn't bend the knee to those obnoxious "recommended instance block" posts they make.
What ppl are talking about today is that the fedilab dev reached out to google and didn't hear back if this gab bullshit would get his app banned so he said he wasn't going to do it. That it isn't the apps place to implement that block.
I agree with his logic. On Firefox today you can go to gabs website, yet Firefox is on the app store. Should firefox block them at the application layer? I think not, and the fedilab guy agrees.