There will be cases where an HTTP status code matches perfectly with an application specific scenario, and in those cases using an HTTP status code is not confusing.

The confusion comes when the API developer tries to shoehorn all application specific errors into pre-existing HTTP status codes.

In most cases it is clearer to simply adopt a payload format that includes application specific error codes, so that the clarity of your API does not depend on its incidental similarity to pre-existing HTTP codes.

422 is a class of errors, not a catch-all for all similar scenarios one might encounter in building an API.