Alright. I wouldn't worry too much, then. If you set it up correctly and you keep it up to date so there aren't any security vulnerabilities, you should be okay.
Of course there are arbitrary, more strict approaches. You could do monitoring. Or restrict the IP addresses the server answers to. Or put everything behind a VPN and not have it exposed in the first place. But I also have my NAS and a few internet services like Nextcloud and it's been fine, similar to this, for years.