Was your phone forced to 990 when they listened on yours?colleagues in my office sometimes take my xm4 (in th past) or xm5 (today) and listen to a couple of songs via my samsung s22 utltra / ldac. they then connect it with their iphone and are confused why "it sounds different"...
my example from above happened around 10 times at work.
exactly, otherwise you compare apples with pears.
Were their phones forced to 990 when they listened on theirs? Also were you both using the same streaming service and quality? If you are on Tidal and they are on Spotify that could explain some of it

This is an interesting discussion and one I have mused on for a while, not just for Bluetooth but codecs in general.