I can't comment on this title in particular but if you load it on your PS5 and receive a toast which reads something to the effect of "when playing on PS5, this game may exhibit errors or unexpected behavior" then it means some part of the game is absolutely fucked up but still "playable."
For example, Star Ocean: Till the End of Time messes up very late in to the game on the PS5 where a space ship environment zooms very far out, the controls become locked in such a way where camera control doesn't work, and directional movement controls seem arbitrarily mapped. While someone more patient and talented than I may have been able to navigate through that issue, I couldn't proceed until I continued the game on my PS4 via cloud save transfer.