Hi Christoph,
Welcome back to the list.
db:drop deletes both, the database and the corresponding backups
The function should only delete database and preserve backups. For deleting backups, db:drop-backup can be used. Maybe there was a bug in an older version of BaseX?
db:info($db)/resourceproperties/inputdate is a UTC dateTime with a time zone offset db:backups($db)/@date is a local dateTime without a time zone offset
Same here: Both returned timezones should be a UTC dateTime with the Z time offset.
Maybe you need to switch to the latest version of BaseX? Feel free to give us an update if the problems persist with BaseX 9.x.
Hope this helps, Christian