Aranym this weekend (for the first time in a year or so) I realized that 1.16.3 under Aranym has the same behaviour. I will try with a if it is reproducible in aranym, it should be quite easy to make a test case, right? ideally, try to install easymint for aranym image, that is available for everyone and we will be sure we have the same test environment...
The problem may be somehow related to interrupt handling in Aranym and Milan. IIRC, Milan handles key-repeat in a different way than the other machines, and a fix was necessary in the keyboard.c for that. IIRC, Ozk has done the fix. So make sure Milan owners use a Milan kernel. For Aranym I can't know, just I never observed problems on Falcon (otherwise keyboard.c wouldn't have seen the light).
Pozdrawiam KMK