Warning on When and Why

Summary: We have an autocomplete rule that checks whether the date a person is resigning is less than 28 days/ 4 weeks (as below). This is a field modification type for the business object When and Why.

This rule works when a date beyond 28 days but if the warning is triggered it appears multiple times and then gives this error when trying to submit.

Our use case was approved but I've seen a few customer connect questions with similar issues and they've been told that warning messages are not supported for When and Why business object. Can we have confirmation if this is still the case for 23D or if there is some other issue?