I am also having the same problem as @William0920. When I updated to iOS 14, the certificate stopped working (I have a self-signed CA and a server cert signed by the CA). It conforms to the requirements (ios13), worked on iPhone iOS 13, until I updated to 14 and currently works on iPad (iPadOS 13).

I submitted a 🐜 to 🍏. In Settings, the certificates (CA + signed server certificate) are both “Verified” (aka trusted). However, connecting to the server with identical server certificate to that in settings, opening the certificate in Safari displays “Not Trusted”!! The certificates are identical (checked sha256 fingerprint), but once “Verified” — Settings, the next time “Not Trusted” — Safari, Shortcuts. ***?