OIDC customization settings not persistent

[mononym]

Hello,
I want to comment out the following entries in homeserver.yaml so that users can define their matrix usernames.

user_mapping_provider:
      config:
        #localpart_template: '{{ user.sub }}'
        #display_name_template: '{{ user.name }}'
        email_template: '{{ user.email }}'

But when restarting the app, the two lines are added again, uncommented, overwriting my changes.