MySQL 8.0.30
Source Code Documentation
Protocol::AuthNextFactor:

Next Authentication method Packet in Multi Factor Authentication

If both server and the client support MULTI_FACTOR_AUTHENTICATION capability, server can send this packet to ask client to initiate next authentication method in Multi Factor Authentication process.

Payload
TypeNameDescription
int<1> 0x02 packet type
string[NUL] plugin name name of the client authentication plugin
string[EOF] plugin provided data Initial authentication data for that client plugin
Returns
Protocol::AuthNextFactor: or closing the connection.
See also
send_auth_next_factor_packet(), client_mpvio_read_packet() send_auth_next_factor_packet(), client_mpvio_read_packet()