Problems with compression of images for ios

Good day! There is a 2D platformer that weighs 50 mb on the android, and ios 1 gigabyte, the problem is that in the unity for ios and android there are different ways of compression the sprites, if not to compress, then ios game will weigh 1 gb, and if to do compression the game will weigh 75mb, but the quality will be very low, tell me please how to solve this problem. Sorry for bad english. Here are two screenshots, the first on the android, the second on the iPhone: