As I expected, many clients will accept Entrust certificates issued after Nov 30. But to my surprise, several providers of PEM root bundles, notably Certifi/mkcert and curl, will begin automatically omitting Entrust roots after Nov 30 - meaning previously-issued Entrust certs will stop working! This is a complete misinterpretation of Mozilla's Distrust After attribute, and will cause unexpected breakage. I have opened bugs, but I expect other consumers have also misinterpreted Distrust After, so it would be prudent to replace existing Entrust certs.