BPM Worklist Notification mode is changing from All to In-App

Several months ago, we continued to see the BPM Worklist setting for Notification Mode intermittently change from All to In-App. It appears to be happening systematically and not by any of our users. We are not aware of any way to audit the field and I'm aware there are idea lab suggestions to add that. The issue seemed to stop happening for quite some time, but now, ever since 25B was applied, we are seeing this happen quite often again. Users are reporting that they are not getting workflow emails, and we find that the notification