I love a good mystery but this should be simple to narrow down immediately, not necessarily simple to answer.
I understand the 5 beeps come randomly.
If you hear it thru your headphones/speakers=software
if you hold your ear close to laptop body when this happens and you suspect it's inside yr box it's hardware.
If hardware it's not always battery-related afaik, sometimes its memory and more..
and why can't it be a 'mac thing'?
you did not say you made any moves in the bios so I'm assuming you didn't.
You said on you first laptop it was 'after login.'
For your second laptop you say no more after login? Just random beeps whenever? Did you say what your new laptop was? if mac, maybe mac thing?
Like I said love a good mystery. If it's the same OS (solus?), on two laptops also running MAC, and both laptops are made by the same company then we'd be somewhere.
Then the weird part would be 'only at login' for laptop A and totally random on laptop B, re: the 5 beeps.
If your gut is saying it's a gnome thing I respect your gut. Why though?
apologies if you answered any of my random questions. i thought i read the thread thoroughly but these work-from-home days short circuit my reasoning sometimes. these random beeps would piss me off, too.