One more try: I have a Hewlett Packard zBook G5 with two misbehaving keys: The unshifted f3 and f4 keys are intended (marked) to decrease and increase screen backlight brightness. However, both operate identically with the unshifted f8 key that (correctly) toggles the built-in microphone on or off.
The error appears at the scancode level: showkey -k reports keycode 190 press and release for all three keys; and showkey -s reports scancode 0x5a 0xda for all three keys; and to restate, all three keys do, in fact, toggle the internal microphone. The installation is vanilla Debian Bullseye except that: a. It is installed on ZFS (including /) b. It uses the nVidia proprietary driver and xorg (Nouveau was very sluggish) c. It is dual boot, with Windows and Debian on separate NVMe device. Grub is installed on the Debian device and boots either Linux and Windows on request. d. Several non-Debian programs (Eclipse, Foxit PDF reader, Ghidra, Google Chrome, and Zoom) are installed on /opt and almost certainly irrelevant to the issue. An oddity is that after a Debian update a few weeks ago, the two keys at issue worked as I would like for a few days, then reverted after I booted Windows and applied the monthly patch set. I do not quite know what to make of that. Suggestions for fixing this defect or how to approach resolving it, will be gratefully received. The zBook is a very nice machine and has only this defect and the apparently insoluble lack of support for the proprietary fingerprint reader remaining. Regards, Tom Dial