I’m not sure if this is going to sound strange, but I’m so accustomed to the voices of different kinds of people that my mind at this point just registers the many different accents as different voices within one accent (as in my mind doesn’t say “oh that’s another accent” anymore, it doesn’t register it) and I actually miss being able to appreciate peoples’ accents as accents, which sucks when for example you’re attracted to them.
Even study accents. Watch some YouTube vids by professional voice coaches. You’ll get to where you can pick out clues about where someone might be from based on aspects of their accent.