While experimenting with ProtonVPN's Wireguard configs, I realized that my real IPv6 address was leaking while IPv4 was correctly going through the tunnel. How do I prevent this from happening?
I've already tried adding ::/0 to the AllowedIPs option and IPv6 is listed as disabled in the NetworkManager profile.
For me, it was rather the opposite: when dropping IPv6 packets, applications would often hang and behave weirdly. Disabling IPv6 completely would mean they'd stop trying to do anything on IPv6 and function well.