I don't know the Android platform but if your app logging shows massive numbers of devices that aren't matched by downloads reported by the Google store add some additional logging to try to work out why.

If the scale isn't large don't worry about it.

It is copyright infringement, you still have your car (going back to your analogy). Also it may be that Aliyun is the used car dealer that has stolen cars but don't know it, the pirates are the ones who uploaded/submitted it to them.

There have been cases on Apple and Google stores of copyright infringing apps although these get removed when reported.