nicopernicus In my attempt to reproduce this, I downloaded the app from Aurora Store and got the same result.
Then, I went to their Website, and downloaded the 64-bit version they have there. It worked as expected.
https://www.retroarch.com/?page=platforms - Under Android, I clicked on the "Download (64bit)" option.
This tells me that they're doing something weird with the version they're distributing through Play Store. It is pretty out-of-date.
All in all, this doesn't look like something that's specific to GrapheneOS, but rather an app (distribution) issue.