In the extension's settings, I have specified WordPress as the
Standard. With the debug pane enabled, I see

Got line from StdOut: The installed coding standards are MySource,
PEAR, PSR1, PSR12, PSR2, Squiz, Zend, WordPress, WordPress-Extra,
WordPress-Docs and WordPress-Core
Found the following standards:
["MySource","PEAR","PSR1","PSR12","PSR2","Squiz","Zend","WordPress","WordPress-Extra","WordPress-Docs","WordPress-Core"]
Found phpcs in /opt/homebrew/bin/phpcs
Running phpcs with the 'PEAR' standard

Any ideas on where this could be going wrong?

Many thanks,
Ash