The amount of posts trying to give Phil credit for this is cringe af. I would also give credit to the fan backlash before even thinking Phil's imaginary role in all this.
MS has a co-marketing deal with GSC and the game is a marquee Game Pass title for 2022, and just one month ago Phil was saying how NFT's are exploitative and they don't want to feature games with NFT's on their store front. Obviously if there was no fan backlash, there would also be no backlash from MS on this, but, like I say, bad press for STALKER 2 = bad press for Game Pass, and MS is going to do everything in their power to mitigate that damage.
I don't think it's unreasonable to believe that there were at least discussions with Microsoft happening as all this fan backlash was occuring, and that it can be the fan backlash as well as those conversations that forced GSC's hand in this situation. Obviously they aren't going to be transparent about what happens behind the scenes with their Game Pass contracts, as they never have been, but it doesn't seem like a huge logical leap to me that they don't want games that bring bad press to Game Pass and XBOX on their services, and there maybe some wording in the contract along those lines that might have allowed MS to pull their funding if a game does have a negative impact on the perception of their service.