Before the acquisition was finalized Microsoft had already stated:
"We want Zenimax/Bethesda games to be first or best on Xbox, exclusivity will decided on a case by case basis"
The reply by some Microsoft fans was : "They're obviously bluffing because the deal is not finalized, everything will be exclusive, why would they spend 7.5 billions??? Once the deal is done it will be immediatly clarified!"
Now the deal is finalized and the message is still the same:
"We want Xbox/PC to be the best platforms to play Zenimax/Bethesda games, only some games will be exclusive"
The same Microsoft fans: "See?? Full exclusivity confirmed!! So much salt and denial"
Honestly it's clear they're leaving the door open pretty much to everything at this stage (full exclusive, timed exclusive, day one multiplatform release but 'free" on Gamepass vs 80$ on PS5 and so on), their main goal with the acquisition is to make Gamepass a success by having many AAA games available day one on the platform, something they haven't been able to convince big third party publishers to do because they would just lose money.
These huge companies do not reason like fanboys, they see the business opportunities and how to make their ventures viable and profitable.
Sony and Microsoft for example have an on going collaboration on cloud services, AI and other stuff. Sony is now making PC games because they see an opportunity there (although they are doing it in a way not to damage their Playstation business) and when they had to choose between going multiplatform and keep the MLB license or refuse to develop a game on Xbox for pride reasons...guess what they decided?
Microsoft needs Bethesda for their Gamepass ambitions, but they realistically do not want to turn them into a money losing business totally sacrificed to the Gamepass cause, they will find a balance.