those IP bans aren’t valid in IPv6
You don’t have to always ban by the full IPv6 address since the other end can be user-changed anyway. There’s a better way called “prefix banning” which bans the first section of an IPv6 address called “prefix”, usually it’s between /56 and /64 for most home networks. Even with the similar risk as IPv4 banning but way better since NAT is discouraged in IPv6 anyway.
I don’t think they do IP ban because IP banning is just not really something that works on IPv4 because a bunch of people on a bunch of ISPs are on CGNAT sharing the same IP address.
Unfortunately Roblox did some automated IP bans since few years ago:
Performance issues with people on certain ISPs that are on just overshared CGNAT, and also, it’s future proofing.
Not just that, but some ISPs already went far enough to completely disable IPv4 and use a translation layer called NAT64 to connect between IPv4-only hosts. The experience feels like CG-NAT but a bit worse, especially for sites/programs that make any use of plain “IPv4 literal” addresses to work.