What do you mean when you say “detect and handle IPv6/64 subnets”?
I’m not too familiar with IPv6 but would love to improve support for it if the project is deficient somehow.
With the original IP, addresses are fairly expensive. With IPv6, even home users are assigned a /64 subnet at the smallest, so a malicious actor can iterate through many addresses. Generally for things like per-IP ratelimiting, you treat a whole IPv6 /64 subnet like you would treat a single IP address.