Does TLS 1.3 really send PSKs encrypted?
PSK is encrypted and normally sent after finished message.
If you inspect with wireshark, it appears as application data.
If you decrypt this message, you will find the session ticket including the psk id.

Servers can use psk id for stateless approach.
Servers can encrypt the resumption psk, issue time, and so on..
and use this encrypted message as a psk id.
When the client present psk id, server can fetch those informations to resume by decrypting it.