weird subviewport behaviour when rendering 3d meshes in ui

Godot Version

4.3 stable

Question

i am using a grid container to implement an inventory. each slot has a subviewport container, which has a subviewport, which has a 3d scene containing a camera and the item’s mesh. my issue is that when i have multiple items rendering, each subviewport is rendering every scene on top of each other. how can i fix this?