Baldur's Gate 3 used motion capture from 248 actors to bring its NPCs to life: 'You’re not only hearing the actors' voices, but you’re also seeing their physical performances'
If that mean they can remove their voices from the game anytime they feel like it, I certainly hope not! And the I don't know what retaining rights for their voices would mean otherwise.
I certainly hope they get justifyingly paid though!
It might have something to do with studios owning the rights to an actors likeness and voice and using them in perpetuity (and maybe even getting the actor to say and do new things with AI) with no compensation given to the actor. It was a big thing a few months ago but I can't remember what exactly it was about.