Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.
ns103.ovh.net ✓dns103.ovh.net ✓
yes
HTTPS over IPv6· not part of the grade yet The certificate served over IPv6 at 2001:41d0:301::29 isn't valid for remembertrenches.fun: ERR_TLS_CERT_ALTNAME_INVALID.
https://remembertrenches.fun/ via 2001:41d0:301::29· ERR_TLS_CERT_ALTNAME_INVALID
problem
What's keeping remembertrenches.fun from an A
www.remembertrenches.fun is an alias of 9b8f01cea532a290.vercel-dns-016.com, which has no IPv6 www.remembertrenches.fun is a CNAME, so it can't also have its own AAAA record. Ask whoever runs 9b8f01cea532a290.vercel-dns-016.com to enable IPv6 there — or replace the alias with the A and AAAA records they give you. Why some hosts don't offer IPv6
The certificate served over IPv6 is wrong The certificate served over IPv6 at 2001:41d0:301::29 isn't valid for remembertrenches.fun: ERR_TLS_CERT_ALTNAME_INVALID. Often the IPv6 address points at a different server (or an old one) than IPv4 does. Make sure 2001:41d0:301::29 serves the same certificate as your IPv4 address.
Mail servers without IPv6 mx1.mail.ovh.net, mx2.mail.ovh.net, mx3.mail.ovh.net have no AAAA record, so mail from IPv6-only servers can't reach them directly. If a provider runs your mail, that's their setting; if you run it, add AAAA records for these hosts.