App removes itself from popup

This has been happening for years now. I have a finance apps popup group on my home screen with 8 apps in it. One app that I keep trying to add to this popup but keeps disappearing is the Discover app. I have no idea why this happens but it seems over the course of a few days/week or so that app disappears from my popup. This has consistently happened dozens of times and I've just given up on having this app in this popup. I've never seen this happen with other apps.