Here’s the specific breakdown from Psyonix: Quality:
It’s not clear if Rocket League now has a new native game client or an enhanced backward compatibility game on PS5. Things have changed since then, so PS4 games can now be made aware of and have different graphics profiles for the PS5 – Zombie Army 4, for example. Well, at the time of release, Psyonix was one of several developers who stated that, while cross-gen awareness was relatively easy on Xbox, for PlayStation 5, they would have to create a whole new version of the game. Even the specific resolutions are a match. That’s a pretty big upgrade for PS5 players, but the fact of the matter is that this is merely catching up to the support that Psyonix has been able to provide for Xbox Series X|S players since December 2020. Meanwhile, the 120 FPS Performance option will drop the game resolution down to 70% of 4K (2688×1512), and combine this with a UI overlay that runs in 4K. Now, the Quality mode will run at 4K with 60fps as the default. Up until this point, Rocket League on PS5 has run through PS4 Pro backward compatibility mode, which has limited the game to running at 60Hz and with 4k achieved through checkerboarding.
