All I am clearly seeing is compression artifacts due to mobile screenshot being saved as heavily compressed JPEG. If you want any help make sure to capture screenshots as PNG instead of .jpg so that we can actually see the defects in game instead of defects badly created screenshot. It needs to be done when creating screenshot, converting existing .jpg screenshot to png doesn’t help since the image is already ruined.
Also please be more specific what parts you are referring to and how exactly are they supposed to look like. Is pc.png supposed to represent how things are supposed to look like? Or do the problems you are thinking about affecting both images? I can spot a couple of different issues even in the pc.png, but those are equally like to be caused by bad Unity config as much as you downloading random insufficient and mismatched quality images from internet.
Regarding the “Mismatched quality images” these were drawn from a friend. The screenshot looks exactly the same as it does on the phone, and not because of the compression your talking about. Maybe a bit, but it’s pretty extreme in compression to screenshotting anything else.
If you zoom into the first screenshot these are clearly artifacts from jpg compression. There is no way it looks that bad on actual device. Blocks are 8x8 and form uniform grid aligned to the top left corner of screenshot. Most gpu texture compression formats don’t use 8x8 blocks, and even if the texture used 8x8 blocks they wouldn’t be aligned in different sprites across the screen. I assume that at least one of the following objects are separate from background picture: the UI with numbers on bottom left corner, moon, horizontal bar at the bottom of screen.