I’ve been dealing with this for almost a year now. The problem started without any apparent cause in my case; no recent BIOS updates or noteworthy system changes.
I went back and forth for quite a while with Framework support; there’s a known manufacturing defect on some keyboards with the delete key. It was very strange that the problem arose randomly, though, if it was a physical defect. Unlike OP’s experience, I found that the malfunction was not completely “intermittent”. Rather, it defaulted to not working, but mashing the key A LOT (like 30+ seconds) seemed to temporarily resolve the problem.
After extensive troubleshooting, Framework reluctantly replaced my input cover, and the problem went away… until this week. Now, just as inexplicably as the first time, my delete key has again stopped working. This time, it seems more completely broken: mashing the key sometimes yields ‘delete’, but only very briefly.
My system is Intel Core 12th gen, now firmware version 3.19.
I wondered whether there was some very subtle software problem (I am also on Arch-based linux), and the fact that OP temporarily resolves the problem by flashing the BIOS (?!) would seem to support that.
@fyredragon69 How do you get the BIOS to actually re-flash? My think that when I try to boot to current firmware update media, it just says, “you don’t need to update”.