Recently roblox updated mobile devices to run GUIs at native device resolution rather than a smaller resolution then upscaling it
If you emulate any device in studio (Take the iPhone 7+ for instance) it says it runs in 746x414. This is true, the world is rendered at this resolution but that’s not what the GUI is rendered at. As a result what would normally look like a 1080p UI is whatever resolution the device renders the world at:
When in reality the world still renders at that small 746x414 resolution, but the GUI would look more like this (1080p GUI, much more detail, especially the text)