How to fix
You need a TLS library with ML-KEM. Quickest routes: upgrade to OpenSSL 3.5 or newer, use a server built with Go 1.24+, or put a proxy such as Cloudflare in front of your site.
nginx (OpenSSL 3.5+)
# check first: nginx -V 2>&1 | grep -o 'OpenSSL [0-9.]*' (needs 3.5 or newer)
ssl_protocols TLSv1.2 TLSv1.3;
ssl_ecdh_curve X25519MLKEM768:X25519:prime256v1;
Apache httpd (OpenSSL 3.5+)
SSLProtocol -all +TLSv1.2 +TLSv1.3
SSLOpenSSLConfCmd Groups X25519MLKEM768:X25519:prime256v1
Caddy / Go 1.24+
# X25519MLKEM768 is enabled by default in Go 1.24+ crypto/tls.
# Upgrade Caddy (or your Go server) to a build made with Go 1.24 or newer.
Cloudflare / CDN
# Cloudflare negotiates X25519MLKEM768 with browsers by default.
# Proxy the domain through it (orange cloud) and scan again.
After changing the configuration, scan again here to confirm the grade is A.