The issue is that 3rd parties are very wary of locking themselves in with Xbox after some really bad exclusivity agreements during the early days of XBone.
The previously mentioned Tomb Raider deal nearly killed the franchise. Square Enix was lucky that anyone still cared about TR a year later when they were finally allowed to release the PC and PS versions. TR is a franchise closely associated with PS from the early days, it was one of the games which cemented the status of the PS1 along with Final Fantasy VII. Trying to force it on Xbox was a total disaster for Square Enix, it's no wonder they will never again stray from PS exclusivity.
The deal for Titanfall literally killed that nascent franchise. I don't think Titanfall was really that great but locking it to Xbox when the majority of gamers were still pissed about TV TV TV and Always Online/No Used Games was a terrible decision. In the end, Respawn became little more than EA's new Star Wars studio making titles in existing IP instead of a new franchise. Jedi Fallen Order and Survivor are pretty good games though despite their technical issues, it's clear that Respawn weren't very technically proficient from the state Titanfall shipped in also.
So MS has the problem now of 3rd parties not wanting to touch Xbox for any price because it's literal poison to their futures. This is one reason why MS has resorted to straight up acquisitions, it's unlikely Bethesda would have ever agreed to any timed exclusivity agreement for anything in the current environment. So now MS is forcing Redfall and Starfield onto Xbox by having Bethesda as a wholly owned subsidiary, let's see how well those games sell when they are no longer on PS and are forced to be Day 1 Gamepass.