The underside of an open chest's lid appears to be several of the Lootr textures stitched together. At first I thought it might be due to a resource pack I'm using (New Default+), but I see it without the pack enabled as well. Screenshots below.

What version of Minecraft is this, and what version of Lootr?

EDIT: Additionally, what mod loader are you running?

This doesn't appear to be happening in my development environment with Forge for 1.20.0. Are you running any other mods?

Whoops, sorry. This is Fabric, 1.20.1, and version 0.7.29.75 of Lootr. This is in a modpack, so there are other mods involved, yes. Off the top of my head, I don't know of any that would (in theory, anyway) affect the texture atlas like this, but if it is not happening with just Lootr, I can do some digging to see where the incompatibility is.

If you have this problem still, please open a new issue.