Hello, I looked a bit at the problem, but I have no clue as to why the Linux kernel Makefile-based module build system changed behavior, and nothing seems to have changed on this driver's side (its Makefile has been untouched for about a year).
Perhaps the problem is more general to our linux-module-build-system and Linux-libre 5.14 (I have it running still on 5.13). I opened an issue with upstream here: https://github.com/aircrack-ng/rtl8812au/issues/893. Thanks, Maxim
