Yeah, there's some delineation in those apps. I notice the same behavior when I hover over the "maximize window" icon in Windows 11 and some apps show an outline of the options of I have but electron apps including chrome
At lease for the function that trigger by hoving maximun button. I believe windows do expose this api, firefox has this enabled for years even they draw the whole screen include icons using xul. And electron apps in native resize button mode also use actual windows resize button (Or fake one created by electron itself?) that has this function enabled. It's just some million-dollor company that are too dumb to support it properly (Or probably PM pushed it back because no user requires it?)