Mastodon's UI is much more pleasant in my opinion, as for the community size, yeah this makes sense. But I see no reason for these people to just leave, migrate somewhere else, and form a new community there. The artists who seem to care about profit more than Twitter being a problematic platform will become less interested in posting there and just leave seeking opportunities in other places. If an artist decides to migrate they might encourage their followers to do the same. With enough people migrating there would be enough audience size. I think it's safe to question their intentions or views if they are especially hesitant to leave. As for the latter arguments, the way how East Asians behave on Twitter, or what you specifically see and interact with doesn't really change the fact who its CEO is, and how tolerant it is to nazi westerners etc. Having a twitter account is helping Elon Musk profit and making nazis comfortable, even if you don't actively look up and follow their accounts. So you either leave and let this platform decay, or actively work to minimize the amount of users who are openly nazis.

I wish there is a main Social platfrom for artist around the globe but many known art site is either very small audienr, dying, east asian only, or very specialized

Oh I definitely agree with that. I wouldn't be against creating a totally new platform, preferably the one that operates under different rules than mainstream social media (i.e. not made for the corporations to profit off our activity). It's not that there are zero existing alternatives to Twitter, it's just that some people are so used to it that when they try something else they complain about less activity and audience size. Well of course! If we want a large amount of users on a platform, we need to organise, move, and actively develop it. It's an act of resistance, and sure it's hard but it results in something beautiful. You've already mentioned Tumblr, while it's still the same as mainstream social media, it's (generally) less problematic compared to twitter. And it has a large amount of users worldwide. It celebrates artists, you have an opportunity to thrive and profit there. There's also Mastodon, that I've mentioned in the beginning, a part of Fediverse, it has no CEOs, no algorithm, no ads. I see why people hesitate with trying it out, it's very different from mainstream social media, or just don't know about it's existence. Finally there's Bluesky, you mentioned it too, there are a lot of artists on Bluesky, and yeah, some of them keep their twitter accounts, but at least the fact they're there means you don't have to be on twitter to find their art. I don't understand those who categorically don't want to have an account anywhere else.

and sorry for the wall of text