Today, after hearing multiple users' similar problems with the game, I woke up and turned on my PC and did a double-check in the usual offending file paths to see if PSO2 had either uninstalled itself or duplicated itself.
(Those file paths being %\Program Files\WindowsApps\Mutable , %\Program Files\WindowsApps\MutableBackup, %\Program Files\ModifiableWindowsApps. AND some folder in WindowsApps marked "100B7A24.oxyna_126.96.36.199_x64__wyfsmff9ynw7j"
I needed to take ownership of the file permissions by using a 3rd party program. Anyone having this problem should consult this Reddit thread: https://www.reddit.com/r/PSO2/comments/gsasu0/how_to_fully_remove_pso2_from_your_pc/
Note: Do not delete the entire WindowsApps folder on your C drive, as it contains numerous other files and folders for many other programs on your PC. Look for the "oxyna" subfolder, and the Mutable and MultableBackup subfolders and delete ONLY THEM. )
Unfortunately, I found it had duplicated the entirety of the game's files onto a drive I did not install it on. A full 70 gigabytes of data just appearing out of nowhere. I installed it onto the D drive which created these folders, and I found them on the C drive today for no reason.
When uninstalling it using Windows' Add or Remove Programs function, selecting "uninstall" did not remove any of these files, leaving 140 gigs of clogged up space on my PC. I repeat, if you uninstall normally, double-check to ensure these files are removed properly.
I love this game, but I can't be dealing with that. You can't expect users to constantly delete swaths of data that they need to wrestle system permissions out of Microsoft's hands to even get at. To expect your user base and customers to go through this much trouble just to play your game is not only unacceptable, but it's downright humiliating for everyone involved. Microsoft and SEGA should be ashamed of this, and if they've got even a shred of integrity, they need to fix this ASAP and be fully transparent about it.
I will not be playing this game otherwise, and I will actively be telling people not to pick it up until a definitive, sure-fire fix has been presented. Ideally, this fix would mean no Microsoft Store at all, but even if it just becomes manageable somehow, I will accept that.
Basically, until users at large report that things are all clear, PSO2 is dead to me, and not by choice. Were there anything I could do about it, I would.