Hi,
there's an issue with the overlay when playing on blocks far away from the spawn. I believe it's a floating point number accuracy issue - if you just layer each X next to another from 0, it might be hard to calculate for the game at such faraway places.
I hope you can fix this. I'm playing on 1.16.5 and discovered the issue there. Maybe it also appears on other versions, feel free to add where else it occurs.

I recorded the outcome in-game plus my journeymap coordinates on my map. Try with comparable coordinates. I managed to get this by setting the spawn radius to 1.000.000 blocks and let myself respawn few times.

I've fixed this issue in the next release for Minecraft 1.20 that will be available soon. I'll also release the fix for 1.16.5, 1.18.2, 1.19.2 and 1.19.4 soon.