Optional compound field validation message pops up immediately in 13.4.2

We've just updated to 13.4.2 (from 13.4.0-1) and we noticed a change in validation behaviour in the CMS.

We have a document with a optional compound field. The compound has mandatory fields. When the editor adds the field to a document in the content, the message "This document has 1 error" immediately appears in the top and the mandatory field is highlighted.

Is this intended behaviour? We are used to getting this error when trying to save a document with missing mandatory fields, but in this case, we didn't even have the chance to fill the field before the error appears.