Finally we merge the 1.21.2/3 branch which has been usable since the version came out but missing the last few changes for over a month! Thanks to all who tested the in-progress branch :)
The Minestom permission system has been removed in its entirety. The system was not very flexible or compatible with existing standards (ie LuckPerms, basic rank enum). We made the decision to remove the system and force libraries to provide their own API for testing and modifying permissions as opposed to attempting to create an overly generic API to accommodate all use cases.
See #2302.