Bruv. I’ve packaged software for all 3 and beyond.
Which btw is completely irrelevant here so get off your high horse.
There’s clear performance differences between 6.1 and 6.6.3 Why? Because there’s several performance related patches & bug fixes that effect various APIs both Wine & Proton take advantage of.
Ofc, you can install newer kernels, you could install kernel 6.6.0 if you wanted, but you’d be going outside of the stable repo to do it which kinda defeats the entire purpose of Debian Stable. Not to mention that mixing and matching packages can lead to problems in the future. Like accidently using the wrong dkms driver version on the wrong kernel version, and other general compatibility issues.
I take it that you’re not active in the kernel development space, which is fine. However I personally am. Hell, there’s going to be even more of a noticable difference in kernel 6.7 thanks to FUTEX2 improvements.