Layers' opacity changes with 3D camera moves?

Do you have motion blur enabled on the apples or the tree?  The layers' samples can overlap in unexpected ways on 3D layers.  To overcome this, you can place an adjustment above the apple layers and below the tree layer in the timeline.  This disrupts the renderer's use of Z-depth to determine composite order and forces it to switch back to the 2D back-to-front composite order.  Any 3D layers that don't have a 2D layer between the, are composited farthest to closest, but 2D layers must be composited in the order in which the layers are stacked in the timeline.

Just keep in mind that any 3D layers below the adjustment layer on the timeline will be rendered behind it, and any stacked above the adjustment layer will appear in front, regardless of their distance from the camera.

At the very least, push those apples a little further back in space.