When I run vendor/bin/phpcs -s --standard=MO4, I get this warning message:
WARNING: The MO4 standard uses 1 deprecated sniff
-------------------------------------------------------------------------------
- Generic.Functions.CallTimePassByReference
This sniff has been deprecated since v3.12.1 and will be removed in v4.0.0.
Deprecated sniffs are still run, but will stop working at some point in the future.
ERROR: You must supply at least one file or directory to process.