I'm one of the people that Mastodon-social has removed posts for speaking out against the genocide.
There are many other cases too.
I'm sorry I'm not aware of a database of such instances, but if you've been here following the issues, you will have seen for yourself.
Mastodon-social in particular is badly behaved on this, and people tell me it is because it is a German instance or the admin are German and Germany has a particularly irrational stance on genocide.