You're not taking into account those that play on mobile and on PC. I have friends that use Game Pass Ultimate and only play on their smartphones and tablets, then there's those that only play Game Pass on PC......the Xbox ecosystem userbase is much larger than you're giving it credit for, and is only going to keep growing.
And actually Square Enix straight hasn't payed the developer without an explanation, leading to speculation that Square just pocketed the Game Pass deal money and the developers only get profit from straight sales, which some could blame Game Pass for that, but it was released on PC, Stadia, PS4/PS5 as well. It shouldn't have had much of an issue making a profit with that type of multiplat userbase.
Look at MLB: The Show 21 which was Game Pass day 1. Profits escalated dramatically for Sony, which I'll attach a story for. I can't seem to find up-to-date numbers, but as of July 28th, 4 million copies were sold. 2 million copies were on PS4/PS5 and the other 2 million copies were on Xbone and Series X/S. Not bad for a console lineup that is dramatically lower in install base. MLB The Show 21 Xbox Release Has Been Huge for Sony Profits (gamerant.com)
I think you are mixing sales with playerbase on the MLB, but will check the link you posted.
Yeah, I actually misread that lol specifically the words were, "Of its 4 million players, MLB The Show 21 sold two million copies on PS5 and PS4, with the other half coming on Xbox Series X/S and Xbox One" I missed the "4 million PLAYERS" part lol but the game on Xbox definitely did bring Sony more profit of the game.