Skill tree display using GPU, causing issues with unwanted fullscreen in PoB and FPS drops in-game

I have an (nvidia specific?) graphic issue - for the last year (or longer, I have no memory), the app has been running in some sort of 3d accelerated manner that makes use of the GPU for the skill tree display.

This is on Windows 10, latest updates, 3080TI Reference, AMD 5900x, 32gb ram system, triple monitor system - but it has been happening (same PC) for at least a year.

Or at least, I think that's what's going on, this is just a guess, because I don't know what else is causing this issue:

PoB will sometimes start up as a fullscreen app, and refuse to go windowed unless I pull some windows-fu on it (using windows hotkeys to move it to another window, maximizing it there, alt-enter won't work if it happens on my main monitor, and I can't figure out any other way to get out of fullscreen).

There's more too - even when not fullscreening itself, it appears to occasionally interfere with overlays in-game, or something about it interferes with fullscreen borderless in-game, either way it'll occasionally tank my fps and I cannot figure out why.

I apologize for the incredibly mushy bug report, but this issue is so strange I don't know how to write up a full repro with any coherence.

I'd be happy to provide more system/setup details if requested, this bug does make PoB noticeably more irritating to use.

No source file, test, or entry point is named. Start by reproducing the behavior on the reported Windows 10, Nvidia 3080 Ti, and triple-monitor setup while viewing the skill tree, then determine whether PoB causes fullscreen changes, overlay interference, or FPS drops; done means the issue is reproduced with a coherent trigger and the unwanted effects are prevented or clearly narrowed down.