Certificate pinning?
Also all let’s encrypt certs are public. So if someone malicious gets a cert for your domain, you can notice.
(Thats also why it may be a bad idea to use that for secretButPublicStuff.Yourdomain.com certificate transparency logs are a great way to find attack surface.)
edit oh certificate pinning has been deprecated in favor of checking transparency logs.
If qbits double every year, we’re at 20 million in 15 years. Changing crypto takes a very long time on some systems. If we’re at ~20000 in 5 years, we better have usable post quantum in place to start mitigations.
But I’m not convinced yet, we’ll have those numbers then. Especially error free qbits…