The new update the SSE executable is probably to allow Xbox Achievements and to allow you to log in with your Microsoft account. Skyrim's new Game Pass executable is 1.5.111, while the steam version of the game is 1.5.97. Update: SKSE will need to be updated to support this new version, it will also need to be modified to load with SkyrimLauncher.exe.
I have not tested using SKSE yet, i will report back with those findings. Allowing you to mod it like any other version of it. In gamepass app if you click on the 3 dots beside the 'play' button, it will give you an option to 'enable mods' doing this will give you full access to the root Skyrim SE folder including the SkyrimSe executable. So I downloaded the gamepass version just to see what kind of modding access they allow.