Isn't it though? They weren't contributing before and they weren't paying Redis corp before, now they are at least contributing to a fork (and still not paying Redis corp).

Presumably some of the things being worked on in Valkey, etc can be upstreamed back to Redis in some form (not entirely straightforward since it is a hard fork with a diff license, but concepts can be borrowed back too).

e.g. apparently Valkey has introduced some performance improvements. Redis can implement similar if it seems worthwhile. Without the fork those performance ideas might have never surfaced.