This is according to the patch notes of update 1.06 for the game. The 3D audio has been temporarily disabled due to a technical problem, although it is not clear what the problem is. “The option will be made available again once the audio issues are resolved.”
It is the second time Codemasters has an option in the PS5 version of F1 2021 should be turned off temporarily. Last month, the company temporarily disabled in-game ray tracing due to performance issues. Last week, with the arrival of update 1.05, it was re-enabled.Full patch notes can be viewed here.

