Rocket League is getting a fresh update later today, finally fixing the PS5's 120fps performance mode. Having initially been promised last month alongside Ratchet & Clank items, PS5 players soon found this new option wasn't working, implementing the lower 2688x1512 resolution (70% of 4K) without a framerate boost.
Accordingly, Psyonix has begun working on a fix and now, they've advised an update for all platforms - PC, Switch, Xbox One, PS4 and (via backwards compatibility) PS5 and Xbox Series X|S - that'll go live at 4pm PDT / 7pm ET / Midnight BST.
New Rocket League Update Deploys Later Today, Fixing PS5's 120fps Performance Mode
Previously, Psyonix's PR & Events Specialist, Will Chan, had confirmed directly to Gfinity:
After working on the issue this week, the performance mode bug preventing 120 FPS play will be fixed in an update coming in early September.
Considering we've now reached mid-September, it's possible Psyonix has found this trickier to implement than they'd realised. Furthermore, this patch also removes voice chat from all platforms, though its currently unclear why Psyonix has done this. Full patch notes are promised at a later stage.