Hear me out...
What if Godot attacked with nodes and the bomb is/has a timer node, the explosion is the signal going off 🤔

Iirc, multimesh lods and frustum culls all the meshes at once since they count as one object. Are you doing anything to help that? :o

You can actually see them on the controller if you try to, it's just a little difficult haha. They're also on the console iirc