Windows 10 Behaves as if Ctrl Held Down

As of late, my desktop computer has begun behaving ~30-60 minutes after reboots as if I am holding down the control key indefinitely. I have seen this question, but its workarounds and solutions did not assist me, nor did googling as what I found there was generally the same list of solutions. The only thing I've found that "resolves" this is rebooting, and even then, it is only briefly. The problem seems to begin only when I am actively using the computer, but does not appear to coincide with an actual press of the Ctrl key.

I have tried unplugging and replugging my keyboard. I've disassembled my keyboard and verified that the button is not physically stuck. I've tried using software to rebind the left control to right control (which I ordinarily never use) and it still persisted. I've run Microsoft's keyboard diagnostics which returned nothing.

I've pulled up the on-screen keyboard and verified that both control keys appear to be held down indefinitely. If I tap either key on the physical keyboard, those keys flash off momentarily on the on-screen keyboard, but then go back to being highlighted a moment later, as if Windows somehow still thinks the key is being held down somewhere else. I've found that if I can get the timing right (which usually requires 20-ish attempts), I can get a keystroke on the physical keyboard to slip in while Ctrl not highlighted and actually use the key as if Ctrl was not being held.

Manually clicking the key on the virtual keyboard seems to do nothing at all. Using software to spam key up/down messages does not resolve it.

Sticky keys, filter keys, etc, are all off.

Windows is up-to-date and security scans have detected nothing. I'm approaching the point where I'm fearing I'll need to repair/reinstall Windows. Is there any other action I can take before that point?