there is an issue where once you are removed from a group you still have that groups permissions I just tested it with the admin group (group that gives all perms)

I set myself as admin tested that I had all commands and perms then removed myself from the admin group and I was no longer in the group but I sill had all the permissions of the group

using Pex sponge for 1.8.9

any idea when this might be fixed?

Unfortunately PermissionsEx is currently unmaintained and no further updates are planned. Because of this, all pull requests are being closed. If you are looking for an actively maintained permissions plugin, take a look at LuckPerms. It is compatible with major server platforms and can import data from PEX.