Comment # 1 on bug 1026032 from Takashi Iwai

Hmm, 12.3 is really old, and it's difficult to find the culprit quickly for
such a wide range...

What shows a value in /sys/devices/platform/i8042/serio*/protocol?
  cat /sys/devices/platform/i8042/serio*/protocol

Also, you can change the protocol dynamically by writing to this.  e.g.
  echo -n "ImExPS/2" > /sys/devices/platform/i8042/serio*/protocol
What happens by this?