Well, from what I understand, it's an extension of the Sega & Azure 'strategic partnership' that was formally announced in early 2022 (initially announced in late 2021), and which the Xbox division was specifically used (such as Sarah Bond) in order to get the partnership in place.
I always took it (well, after initial thoughts of OG Xbox-style exclusives of smaller Sega IP were dashed) to mean that there's be a lot of Sega/Atlus stuff for Game Pass. And that's more or less been happening. But I guess it also extends to Western marketing for games like Persona as well. I might be wrong on the following, but during the FTC hearings some documents came out showing the terms between Microsoft and Sega for their Game Pass deal.
The following is regarding Yakuza: Like A Dragon's timed next-gen exclusivity for Xbox Series in the West:
So it seems like whereas Sony did a timed exclusivity deal, Microsoft effectively got the same through a parity clause because the PS5 version of LAD wasn't ready yet at the time. I'm assuming the PS5 version was a unique build, whereas the Series versions were just the XBO version with BC upgrades, hence how MS got 4 months timed exclusivity.
You can also check out
this thread which goes into the details regarding RGG Studios & Xbox. To my knowledge, this parity clause hasn't been confirmed yet for IP beyond Yakuza but I wouldn't be surprised if it's being enforced on those games (hence why I have many doubts Persona 6 is a timed PS5 exclusive). Combined with the Azure deal that leveraged the Xbox Game Pass unit, I suspect this tied into securing Western marketing rights for various Sega/Atlus titles by Microsoft, which includes Persona 3 Reloaded.
Although I suspect it's basically like an overly extended embargo, where closer to the Western launches Sony can actually advertise those games directly in their own marketing, like they've done recently for the new Yakuza game.
