Currently the PHP coding standard is only enforced through a pre-commit hook and things might be missed.
This step should be enforced by the CI.
PHPCS  is not able to silence an existing set of issue in the codebase. As such, and to avoid too much false-positive, the sane approach  seems to progressively add rule to enforce to fix the corresponding issues all over the codebase.
The existing pre-commit hook will be kept as is to try to do the best it can to detect issues and the CI will enforce a subset of the ruleset.
To test the approach, a new coding standard rule is going to be added: the unused use in the PHP files will now be rejected.