It's extremely common to use bitfields though. As mentioned by the article, it is recommended by ARM's CMSIS and thus found in vendor libraries of all cortex MC

It's extremely common to use bitfields though. As mentioned by the article, it is recommended by ARM's CMSIS and thus found in vendor libraries of all cortex MCUs I have seen. arm-none-eabi-gcc changing its behavior for bitfields would probably break 99% of existing arm MCU codebases.