...
End-user devices need to verify the server certificate. They do this by having a known set of trustworthy anchors, the "Trusted Root Certificates". These root certificates need to be available and activated on the device prior to starting the eduroam login. Therefore, it does not serve any useful purpose to send the root CA certificate itself inside the RADIUS/EAP conversation. It is not harmful to send it anyway though, except that it unnecessarily inflates the data exchange, which means more round-trips during eduroam authentication, and in turn a slower login experience.
...