I think the problem is widespread and simple, the updated software takes up too much RAM for the older Android phones to handle. I couldnt fly since June with my S7, as soon as I got my S9+ with extra RAM, my pixelation problems went away.
According to Wikipedia "Nexus 6P has 3 GB of LPDDR4 RAM" and the iTouch seems to have 256MB or 512MB or RAM. Am I making a mistake here? That would seem to disagree with your point. Have I misunderstood what you are getting at?