I don’t remember whether only the fictional names were shown in-game, if at all. There were a couple radio stations to choose from when driving (there were also some scattered around throughout the game word).
The end credits had more details on performers, etc. and as can be seen some didn’t have a fictional name or had multiple fictional names.
If I had to guess, both the fictional and real artists are credited on music platforms due to statistics, royalties or something like that. Maybe it’s even simpler and rather about recognizability so a player can find it by that character’s name.
See also how rateyourmusic handled this:
https://rateyourmusic.com/admin/corq/?req_id=8996613
So here’s an interesting situation, so for a bit of context all artists in the soundtrack preform under and assumed in-universe alias. Problem is, as streaming sites aren’t album well equipped to take pseudonym’s into account, so we have a mess here they’re officially listed with the original artists AND the in-game alias.
Since RYM does not have this problem, however, I have filled this out in a way best fits how the game’s developer’s and music supervisor’s intended to showcase the artist; 1. Have the tracks be listed as the in-universe alias as these songs are considered canon and not just background music (linking where appropriate). 2. Credit the original artists as songwriters so to not “spoil” who they are but too still give credit.
If you think the artist credit’s are redundant, let me know, but I still think this is the best way to handle this.