Clarify time until Nextcloud's maintenance mode takes effect

In the documentation for creating nextcloud backups you suggest to enable the maintenance mode before starting with the backup process to prevent data inconsistencies.

According to my experience activating the maintenance mode does not always have immediate effect. Only after waiting the time configured in the php configuration value
opcache.revalidate_freq
you can be sure that your nextcloud instance is really running in maintenance mode.

I suggest you should clarify this in the documentation, as automated backups taken by scripts might otherwise not be consistent, if the copying of files or the creation of a database dump is started immediately after enabling Nextcloud's maintenance mode (i.e., before it is effectively enabled). Another solution might be that the
php occ maintenance:mode --on
command blocks until maintenance mode is effectively enabled.

Start with the backup documentation at docs.nextcloud.com/server/stable/admin_manual/maintenance/backup.html and review how it currently describes enabling maintenance mode. Check the interaction between php's opcache.revalidate_freq and php occ maintenance:mode --on; done means the backup instructions clearly explain when maintenance mode is effective and how scripts should account for that delay.