I just found out, that the "access to obb storage" toggle for Apps allowed to install apps, is only on GrapheneOS.
Aurorastore requests permission to "access all files" which is needed on Android to access some privileged directories, like /obb.
This storage is needed to store large files, mostly used by big games. Many people, especially on GrapheneOS, will never need this.
But this is not important, because if you want to download big Games, just give the Appstore permission to /obb using the toggle.
The permission "access all files" is not needed and can be disabled. In general I would never grant it to internet-connected apps.