Computer suddenly behaves as if I were holding down the "up" key consistently

This started today: All of a sudden - nothing specific I did or anything, more like I left the room and the issue was there when I came back - my PC started acting as if I were holding down the cursor up key all the time. This means that things like start menu and file explorer are borderline unusable (I can not access system shutdown, I am forced to do a hardware shutdown if I want to reboot), since even if I click something, it usually selects the item above because it registers an "up" input before the click, and then I can watch the highlight cycle to the top without my doing. It happened this afternoon and vanished after a reboot, now - a few hours later - it is back, again without any inputs from myself.

Details:

- Win 11, nothing fancy or particularly custom. This system has been running without issues for years. - Razer Huntsman keyboard. I *thoroughly* cleaned it this afternoon because I suspected something mechanical, like a crumb triggering the switch, but did not find anything. - Keyboard is connected through a USB switch so I can switch my mouse and keyboard between my personal PC and my work laptop when needed. - Problem is new and started today, I have not done extensive testing (different devices etc) - I don't have a second keyboard to try to replicate it with, but I am using this keyboard on my work laptop as well, so if it occurs there (which it has not so far), I will add it to this thread. - I googled for similar issues, but have not found anything.

I don't really have an idea where to even start with this (aside from looking for some piece of dirt causing this, which I did, unsuccessfully), so I'm grateful for any advice you may be able to provide. My best guess would be some weird USB driver glitch, but no idea what to do about it or even how to pinpoint the source. (Or, of course, a hardware defect.)

Edit: My explorer.exe process just crashed - could be related? Maybe it is a software issue?

Edit 2: I realized I had a game controller connected via USB, which was stored in a bit of a messy place - it did not look like it, but it's certainly possible that something was pressing on the up key and caused this. Disconnected for now, will see if the issue still reoccurs or not. If this thread goes quiet and I don't post a resolution, assume this was it.

Edit 3: Problem did not return after unplugging the game controller. I assume that was it, friendly reader who may find this thread via google years later.