The backend didn't expect AuthSwitchRequest packets in response to the
handshake response packets. This is allowed by the protocol and appears to
happen with at least MySQL 8.0.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.