I’m not on twitter so I hope you won’t mind my questions but why is everyone migrating from there to blue sky?

Here's a several reasons I see.
1. Lots of trumpists and right-wing people nowadays. It can be really annoying, especially for trans-person and LGBTQ+ people.
2. New policy about black list and "block" option don't hide your posts, it's not great for nsfw artist and.. just keeping creeps out from your page.
3. Musk is.. just an awful CEO. Feeding their AI with arts, sponsoring dubious and stupid shit there.
Twitter (X) nowadays feels way worse nowadays.. so I can understand it, even if I'm not using it that much.

Oh boy I thought it was for a same reason a lot of folk were leaving DA do to ads and AI but that all so much worse…also the blocking function detail is one stupidest design decisions I’ve ever heard someone make because it defeats the whole purpose of blocking someone!?!

yep, that's it, sadly.

Very unfortunate to hear, thank you for the information.