This seems really common to be honest. I wouldn't be surprised if there are shops specifically aimed at doing this. I have followed a few indie games where this has happened. Its seems really risky to do a PC only release now, because its only a matter of time before it gets stolen and put on mobile if you are even only moderately successful.

What shocks me is it seems like small creators can have their work destroyed by a single DMCA complaint, but blatant copies like this are ignored.