I have Hetzner and have all my IPv4/6 dual-stack configured correctly, but I'm a big IPv6 advocate. @roboneko is right thought; it's just an additional IP address. It seems like the issue you had was that it was being used for outbound and other servers didn't know how to send things back.

I would recommend getting familiar with IPv6. It's really not that difficult unless you're doing something crazy, like handling multiple IPv4 and IPv6 addresses on isolated docker networks (which I wrote a tutorial for because it's that insane):

https://battlepenguin.com/tech/docker-with-ipv6-and-network-isolation/

I started writing a status page application that would handle both IPv4 and v6 checks to make sure dual-stack setups are configured correctly, but it kinda got kicked to the backlog-of-life™