This is straight up wrong. An IPv4 ICMP echo request over ethernet uses a minimum of 42 bytes, the same request with IPv6 uses 62. The ethernet frame is 14 bytes and the ICMP echo is 8 bytes for both packets, the difference is that the IPv4 header uses 20 bytes where IPv6 uses 40.

Anecdotally, my ping to HN is consistently 166ms with either protocol. I doubt an extra 20 bytes is going to make any meaningful difference to latency, but I'll leave that for the game devs to find out.