StockFish on the phone app vs Stockfish on the computer

So I have wanted to complete the challenge of checkmating with Queen vs Rook (which is in the Learn -> Endgames -> Checkmates -> Queen vs Rook);
I have done much practice and studying on the subject (still much more to do) and I was able to complete the challenge (5 different positions with difficulty increasing) on the phone app about 50 times now with only a normal amount of effort... Yet I cannot complete the challenge at all when playing on the computer website on my PC.

Is the defensive bot (I am assuming stockfish) that is part of the challenge different on the app than on the website?

I'm pretty sure that the version of Stockfish on computers is generally stronger and able to analyze more lines in deeper depth than the Stockfish on your phone.

I think you can lower the strength of Stockfish in your settings somewhere though.