The pages still say Game Pass though, which make most sane people know that the game will be on Game Pass at release. If it did not say Game Pass at all, then we can think it will not be day one.
My guess? They changed the logo due to people thinking Game Pass is just for Xbox. Microsoft's big push is Game Pass, and they want PC gamers and cloud only gamers to sign up as well. By always having Xbox along with GamePass, maybe they are thinking that is making consumers feel it is only for Xbox? The changes happened back in November. So this is not related to the latest rumors. I think it is more of a marketing shift when it comes to GamePass: trying to get more subs. Unfortunately, with all of the rumors and speculation going around right now, it seems to be causing more chaos with gamers.
Another plausible spin on this, although I feel still unlikely, is Microsoft has finally gotten deals in place to have GamePass on other platforms like PS5 and Switch, but part of the deal was to remove Xbox from the marketing. This is plausible, but I really think it was more to get people to see that GamePass is not just for Xbox, so the Xbox part is not so front and centered.