I can confirm that this is still a problem on 1.18.12. I recently purchased a 3rd gen 11” iPad Pro and immediately noticed that x-axis visibility was being severely limited. I also own a 1st gen 12.9” iPad Pro which does not have this problem. Both iPads are running the latest versions of iPadOS and Minecraft. View distance in Minecraft is set to 40 chunks on both iPads. MineCraft on the 1st gen iPad Pro renders properly in all view directions, but loading the same world on the new 3rd gen iPad Pro exhibits the render distance clipping to somewhere around 16❓ chunks on the x-axis (east/west). This is very, very annoying to experience on newer, ostensibly more capable hardware.
Indeed. It works now. Score one point in favour of render dragon!
With my 3rd Gen 11 inch iPad Pro set to a render distance of 40 chunks on Minecraft 1.18.31, I loaded a new flat world and flew to a y-level of 150. Looking around I can no longer see any of the old "culling" behaviour; the horizon renders properly in all directions now.