Using IPv6 outside of Docker with Docker

I recently activated IPv6 on my Netcup VPS, and in the process of setting it up on all my LXCs I noticed that for “reasons” the IPv6 default route would vanish after starting Docker (switching it all over to Podman is on my TODO list), effectively breaking the IPv6 connectivity on this LXC. After some digging this seems to be a security thing: docker will enable forwarding on (eg.) eth0, but s...