Comment by m4rtink

Some sort of undefined behavior or possibly some per build random key that triggers imposter warning if the third party app fails to send the correct key ?

In any case totally evil behavior from their side. Its already bad enough they run totally proprietary centralized service with no public API & ignore any non-mainstream mobile platforms. But when they start banning users of third party clients on those platforms and go after third party client developers with presumably legal treats - that's pure evil, no way around it.