I don’t think Tailscale counts as a reverse proxy, but it does support HTTP/3 and QUIC so that suggestion may not apply here. Still, it might be worth double-checking to see if they are disabled. Also, have you tried disabling Tailscale altogether and connecting directly?
Don’t feel too bad lol. It’s structured to feel like a single player game, which they may have done a little too well. You aren’t the only one to not realize.
It’s such a beautiful game! I need to play it again.