When I built and updated my android game most of the textures became very pixelated. This has never happened before. The GUI Textures are still the same though.
Did you accidentally recompress everything when building? There’s an option under Build settings, where it says it can recompress all the textures to a certain format (ETC, if I recall correctly), and it’s a default option I believe.
Also, check under quality settings and make sure the right one is set to default for Android.