I have been seeing change of behavior on O365 when app is uninstalled. Not sure if anybody experienced the same. Let me explain,
App Uninstall behavior before:
When app is uninstalled, SharePoint deletes it permanently and triggers 'appuninstalling' event receiver immediately
App Uninstall behavior now:
When app is uninstalled, it goes to Recycle bin. If you remove it from Recycle bin (/_layouts/15/RecycleBin.aspx), uninstalling event does not trigger. It triggers only when you completely remove it from Admin Recycle Bin (_layouts/15/AdminRecycleBin.aspx?View=2). So, in order to trigger event you have to completely remove app from recycle bin.
Has anyone experienced the same?