I would consider this a service failure as people on twitter said they couldn’t login but even if you did nothing in the app was up to date. Also it does seem for those affected you couldn’t make payments which definitely makes it a service failure.
My definition of the app failing is not being able to access it at all such as just crashing on startup. Also different sections of the app just not working.
The problem is we will never get an explanation and I doubt they will report this as a service failure.
It seems to only have affected about six people and if I hadn’t been up late and not posted about it I doubt any of us would have known