It leads me to believe that something must be wrong with how YunoHost is restoring from local Backups…
I looked if i could see differences in how Pleroma recommends restoring and how ynh does it, and there are differences.
The Pleroma docs recommend to use pg_restore with the -1 flag while restoring[1]. Ynh doesn’t seem to do that. It just executes the file as is with the psql command and without the -1 flag[2].
With man pg_restore I see the following (The psql command has a similar option)
-1 --single-transaction Execute the restore as a single transaction (that is, wrap the emitted commands in BEGIN/COMMIT). This ensures that either all the commands complete successfully, or no changes are applied. This option implies --exit-on-error.
Whether something really went wrong during restoration, is another question of course. But from what I understand, it’s indeed possible that something went wrong during restoration, but ynh ignores it and just continues.
[1] https://docs-develop.pleroma.social/backend/administration/backup/
[2] To restore, it uses the helper ynh_psql_execute_file_as_root (see https://github.com/YunoHost-Apps/pleroma_ynh/blob/master/scripts/restore#L121)
I see that uses the helper ynh_psql_connect_as (https://github.com/YunoHost/yunohost/blob/dev/helpers/postgresql#L59)
Which in turn uses the psql command (https://github.com/YunoHost/yunohost/blob/dev/helpers/postgresql#L8)