I assume as this is a Gaming mode, its purpose is not to avoid waiting for features. But close the entire desktop which may use up to 1GB RAM and a by of CPU. Which definetly impacts the game by some fraction. Doesnt matter how tiny, its just what gaming modes are having as focus I assume.
The next thing I would never see on a desktop is FSR which gamescope has.
I thought its an entire different desktop. Especially itd not possible to run gamescope while a X11 Desktop is running so I guess you are wrong with “bypassing”. Its just switching to gamescope. Its a Wayland compositor. It does even less than a Window Manager (is this right?)
I guess this is to figure out what is also possible on Linux, and getting to know that not all problems or missing features apply to other distros.
Sometimes you can lwarn amazing stuff, like a KDE distro can be customized to your liking while a Gnome desktop is a nearly forced workflow and design but can be slightly changed with buggy extensions.