Tell you what is strange @SupportiveEntity, take a look at these 3 renders - from one render pass. The first is both foreground layer (forest) and the rest of the scene.
Secondly, we have just the forest scene - however, you’ll see the trees and background rock are missing.
Thirdly, in the rest of the scene - you’ll see the plants are masked out (as they should be) - but there is a feint ghost of the trees - it’s like the trees and rock haven’t been included in the layer (even though they are there for sure)