I thought of this after a recent bug I found. I use Vivaldi browser and recently it updated. After the update my mouse cursor was not visible when within the browser window. Other programs worked fine. I tried visual studio and steam and epic game store all had my mouse, Vivaldi didn't.

I closed all instances of Vivaldi via task nanager(was unable to click the x) and restarted it. That fixed the bug and I haven't been able to replicate so I don't have anything to submit for a bug report. Just a really strange thing.

What have been your weirdest bugs?