Compare the same account action on app and web within a short time window. Note client versions, device, network, local time, and whether the exact same feature fails.
An app-only problem may be related to a release or device setting; a failure on both surfaces may point more broadly, but neither conclusion is certain from one test. Check official status and avoid repeated actions that could later complete twice.
Which action works on one surface but not the other?
Akousa