I do not know much about Timeshift and Lucky backup. But a proper backup is not a on the same system even if it is a second drive internally. For some quick file recovery after deleting things you shouldn’t have it is fine. A proper backup should be a separate system and ideally 2 systems one externally but this is overkill for most folks. With a separate system you can setup automated backups and disaster recovery. if you are scared the backup system can get compromised from the main system. you can set things up in such a way that the backup works in pull mode and the main system being backed up has no access to the backup system.