Here’s a temporary fix:
services.fail2ban.package = pkgs.fail2ban.overrideAttrs(old: {
patches = [
(pkgs.fetchpatch {
url = "https://github.com/fail2ban/fail2ban/commit/2fed408c05ac5206b490368d94599869bd6a056d.patch";
hash = "sha256-uyrCdcBm0QyA97IpHzuGfiQbSSvhGH6YaQluG5jVIiI=";
})
(pkgs.fetchpatch {
url = "https://github.com/fail2ban/fail2ban/commit/50ff131a0fd8f54fdeb14b48353f842ee8ae8c1a.patch";
hash = "sha256-YGsUPfQRRDVqhBl7LogEfY0JqpLNkwPjihWIjfGdtnQ=";
})
];
});