MySQL 8.0.39
Source Code Documentation
Protocol::OldAuthSwitchRequest:
Warning
Deprecated. Newer servers should never send this since they don't support Old Password Authentication and they support CLIENT_PLUGIN_AUTH. Newer clients should not support it since they should not support Old Password Authentication. and they should support CLIENT_PLUGIN_AUTH.

Old Authentication Method Switch Request Packet consisting of a single 0xfe byte. It is sent by server to request client to switch to Old Password Authentication if CLIENT_PLUGIN_AUTH capability flag is not supported (by either the client or the server).

Payload
TypeNameDescription
int<1> 0xFE (254) status tag
Returns
Protocol::AuthSwitchResponse: with an Old Password Authentication hash or closing the connection.
See also
client_mpvio_read_packet()