It seems VRR is a bit of a 'get out of jail card' for devs in terms of the Series consoles. I mean sure if you have a VRR TV its great.
I wonder if some devs feel they have to puch rez higher on XSX or they may get criticized of being PS5 biased, or not using XSX to its fullest etc.
There are cases, and not a few, where XSX has the advantage of resolution and also the same or better framerate...
I don't think it has anything to do with the developers' choice and simply It is a product of circunstances in the development and optimization of the different versions that cannot be exactly identical either.
It is simply that, no matter how similar they are in hardware, they have some difference and also use different APIs. The DRS margins may not work the same, that in specific situations the game code is simply more friendly with the tools of one or the other...
In general, at least as seen in this year and a half, they are possibly the most even consoles in history. Having the exact same architecture and technology it is not surprising what you are seeing.
But no matter how similar they are, there are always aspects that make it very difficult or impossible to make 100% identical versions.