Vertical facing surfaces appearing at wildly different places than they are in the world

In the End dimension, on my Carpet 1.20.1 server, I've been building this obsidian ring at y:0 to cover the void for a future mega project. Distant Horizons renders the sides of the ring at the correct y value, but the top of the ring is rendered at y:40 for some reason. I've tried fiddling with the settings, like setting Vertical Quality to Extreme, but nothing that I tried changed it. I have replay mod installed, but I had this problem before that. Attached are 3 images, one showing what the area actually looks like when rendered in (with Distant Horizons disabled), one showing the platform being rendered 40 blocks too high using Distant Horizons, and the third image shows a side angle, that shows that the sides of the blocks render correctly, for whatever reason.