I've mentioned this before I believe, but as someone who spent the better part of a week trying to fix a couple of installs with Forza Horizon 4 and Gears 5, I can say with confidence that, yes, the Windows Store/Xbox GP app is trash. The backend is a fucking mess of restricted permissions, strange file relationships, and scattershot dependencies.
For example, "ghost" DLC add-ons can completely fuck your install. You can't get rid of them because they don't exist on your drive, but you can't reinstall them because... Windows thinks they exist on your drive. So you're stuck in this weird limbo where you can't do anything because Windows doesn't know what to do with apps/add-ons that claim they're installed on your system. This either means you have to reformat that drive or partition, or painstakingly go through the internal Windows Store database and manually remove all related entries from the table, not to mention the registry.
Oh, and by the way, Fun Fact: Windows will refuse to work properly if you don't have certain default apps installed (apps you
don't need to run Windows by the way). Found that out while on this Windows Store adventure.
Anyone who says that PC Game Pass/Windows Store/Xbox app is "fine" and "it's just you, you don't know how to configure windows properly" is full of shit. Period. No other games store has this problem with letting a user manage installed software, just Windows.
You need to be extremely careful when trying to manually delete windows apps or you could fuck up any other installs in that folder.
The better solution, as
Duxxy3 mentioned, is simply to have a drive or partition 100% dedicated to Windows Apps. That way you can nuke it should apps start behaving badly. It sucks, yes, and is still ridiculous, but it's better than reinstalling Windows or having to go full System Admin to fix a broken game install.