Mac dualboot with Kali Linux: jack with red light
This is a long standing linux driver issue.  I installed linux on my first macbook back in 2008.  The optical audio light was never on before and it never went off after I ran linux.  Even after wipe and reload of OS on a new hard drive.  You can complain to the ALSA developers but you probably won't get anywhere.  I never had audio problems because of it, everything worked fine except that light was on.  You easiest solution is to ignore it or put a plastic plug in it.