Is your feature request related to a problem? Please describe.
Problem is the user_external developer doesn't have time to develop the app anymore so this app will probably be obsolete very soon.
Describe the solution you'd like
Some documentation on how to remove this app while retaining the possibility for accounts that used to login via an user_external backend to login and keep their data.
Describe alternatives you've considered
Manually create new accounts and migrate data by hand from the user_external accounts to the native Nextcloud user accounts.
Is your feature request related to a problem? Please describe. Problem is the user_external developer doesn't have time to develop the app anymore so this app will probably be obsolete very soon.
Describe the solution you'd like Some documentation on how to remove this app while retaining the possibility for accounts that used to login via an user_external backend to login and keep their data.
Describe alternatives you've considered Manually create new accounts and migrate data by hand from the user_external accounts to the native Nextcloud user accounts.