Would you care to help?

It'll get ported when it gets ported, and a 'bug report' like this comes across as a little bit rude.

As with all minecraft mods, this is an entirely volunteer-run project, and poking us with a stick isn't going to do much to speed that up.

Believe me, I'd like nothing more than to see blood magic on 1.21, but until Way's back from his hiatus, or someone volunteers to step in and help out with the porting, all we can do is wait, and I must emphasise this, patiently.