As someone explained the certificate isn't part of ServerHello.
After ServerHello is sent, the server knows a client now has everything it needs to establish all the keys, so it encrypts all subsequent data.
The pretence that this is just a TLS 1.2 session resumption continues though. So there's a wrapper shown in the document. This wrapper claims to be TLS 1.2 encrypted application data. In fact it's TLS 1.3 encrypted handshake data. For clarity in the document they show both the whole encrypted wrapper, its decrypted data, and then the separate components inside that decrypted data.
After ServerHello is sent, the server knows a client now has everything it needs to establish all the keys, so it encrypts all subsequent data.
The pretence that this is just a TLS 1.2 session resumption continues though. So there's a wrapper shown in the document. This wrapper claims to be TLS 1.2 encrypted application data. In fact it's TLS 1.3 encrypted handshake data. For clarity in the document they show both the whole encrypted wrapper, its decrypted data, and then the separate components inside that decrypted data.