Hold your horses, that is just lens distortion
There is always an Apple user, using his new iPad/Apple watch/ iPhone, and getting it damaged after slight use, and never saw or felt it happening,
there is no reincarnation of Urie Geller, working in one of the Apple factories,
you are just unlucky, buy a better case for it, and move on.
I have my new iPad pro, with only a soft sleeve, inside my backpack, that is positioned right up against my back, I have been commuting every day for 2 weeks, in train/bus/subway, and even leaning my back, with backpack, against a wall on the subway every day, and my iPad is still straight