This is because according to Apple who confirmed with MacRumors, when connecting to less powerful iPads that come with a USB-C port, like the fourth-gen iPad Air and the new iPad mini 6, the resolution you will get is 1440p. To be honest this isn’t too bad, but for those who were hoping to leverage the full 5K resolution, those older iPads will not cut it.
This is because the USB-C ports used in the fourth-gen iPad Air and the iPad mini 6 can’t achieve the required data throughput to hit 5K, so it will be limited to 1440p. We reckon for the most part most users should be fine at 1440p, but if you were buying the display just to connect it with your iPad, you should probably get one of the newer models.
According to the tech specs for the Studio Display, the monitor will be fully compatible with iPads like the 12.9-inch 3rd gen iPad Pro, the 11-inch iPad Pro, and the newly announced iPad Air fifth-gen.