Using the CLI script admin/cli/restore_backup.php led to this error:

Default exception handler: Fehler: Sie haben aktuell kein Recht, den Termin zu aktualisieren. Debug:Error code: generalexceptionmessage* line 106 of /admin/cli/restore_backup.php: moodle_exception thrown
!!! Fehler: Sie haben aktuell kein Recht, den Termin zu aktualisieren. !!!

Which basically means a permission was checked and the user is not able to continue the restore. In this case the reason for the error is the mod_zoom plugin which creates the calendar events upon restore without telling Moodle to not check for capabilities (see https://github.com/ncstate-delta/moodle-mod_zoom/blob/c7dba4307c31ccf894914e46aca184d77ea6492b/lib.php#L553)

But it seems the more reasonable method to prevent something like this in the future would be to setup the main admin user as $USER in the restore_backup.php script.

Or would this lead to other problems with artifact ownership or something else?