1440x1440 is 2k, as is 2048×1080. It refers to the total number of pixels. 4K is 3840X2160, but you wouldn’t be wrong to call 2048x2048 4K, especially in a VR

1440x1440 is 2k, as is 2048×1080. It refers to the total number of pixels. 4K is 3840X2160, but you wouldn’t be wrong to call 2048x2048 4K, especially in a VR display where you have two displays, doubling width, and in the end what matters is pixel density.