So when I opened my pngtuber in the app I started playing a game only for my model to completely freak out and stretch out as though the parameters of the bounce were suddenly gone and the character shook itself into a mess of pixels

This just... happens. I'm not sure the cause of it, but I think its from FPS irregularities in PNGTuber Plus from your PC divying up resources between the app and the game you're running. Less graphically resource intensive games tends to have less chance of making the model explode and going - as my chat likes to call it - biblically accurate. 

The dev has implied that he might have a fix over twitter, I think, so maybe we'll see a fix soon!