There are multiple reports stating that id software has been hit the hardest, with almost all of their programmers (and many artists) having been laid off.

pushsquare.com/…/legendary-dev-id-software-allege…

It looks like Xbox management doesn’t see the point in id having their own engine anymore, which certainly is a decision.

I’m not sure what to think of future id games being based on Unreal (like Halo and everything else), which is the logical conclusion to this. So much of the studio’s identity is tied to their proprietary engines, which have always been industry-leading.