Also, just noticed: when changing field types, fibery actually deletes and recreated a new field. (One-to-many → many-to-many, for example). This breaks the field usage in places just like “Delete” does, but it does not get the same popup saying things will break.
Tbh, there isn’t much you can do, since you need convert it anyway, and then fix. In which case, you’d need this: Notify/show broken formulas in rules BEFORE they fail
The main case is Field Updates and “Add to collection” automations. Since it does not throw any error until runtime.