MySQL 8.0.30
Source Code Documentation
Protocol::AuthSwitchResponse:

Authentication Method Switch Response Packet which contains response data generated by the authenticatication method requested in Protocol::OldAuthSwitchRequest: packet.

This data is opaque to the protocol.

Payload
TypeNameDescription
string<EOF> data authentication response data
Returns
Protocol::AuthMoreData:, ERR_Packet or OK_Packet

Example:

If the client sends a Caching_sha2_password information and the server has a Native Authentication for that user it will ask the client to switch to Native Authentication and the client will reply from the Native Authentication plugin:

14 00 00 03 f4 17 96 1f 79 f3 ac 10 0b da a6 b3
........y.......
b5 c2 0e ab 59 85 ff b8
....Y...
See also
client_mpvio_write_packet, server_mpvio_read_packet