On a 1080p screen at 100% UI scale, Factorio uses the second mipmap level to display icons in inventory, since the icons are 32x32 pixels at that resolution and scale.
Factorio also automatically assumes images that are wider than their icon size must contain mipmaps (pretty sure that came with the high res sprite change in 2.0).
So, since the icons use the same image as the spritesheet, on lower resolutions Factorio would display the top-left corner of the right arrow instead of the up arrow as the icon.
The fix: crop out the first 64x64 pixels of graphics/arrow.png, graphics/loader/arrow.png, and graphics/double-arrow.png, and save them as graphics/arrow-icon.png, graphics/loader/arrow-icon.png, and graphics/double-arrow-icon.png. Then locate the places in EntityBuilder.lua, ItemBuilder.lua, and RecipeBuilder.lua where these files are used as icons (but not platform_picture or sheet), and replace them with the -icon variant.
This made Slim Inserters look right on my ROG Ally handheld, a place where your SpeedyBotStart modpack/quickstart feels more like an accomodation to the slightly klunkier controls of the gamepad than a cheat.
