I created two scenes, one for two 2d renderings (Orthographic Camera), and one for 3d rendering(Perspective Camera), I applied an effect on the first scene (2d), and then I checked autoClear=false so I could render these two scenes
the code in the updated function
boxMaterial.uniforms.time.value = elapsedTime
renderer.setRenderTarget(RT_A)
renderer.clear()
renderer.render(plane, quadCamera)
renderer.clearDepth()
renderer.render(rtScene, compCamera)
renderer.setRenderTarget(null)
quadScreen.material.map = RT_A.texture
const rt_temp = RT_A
RT_A = RT_B
RT_B = rt_temp
planeM.uniforms.tDiffuse.value = RT_B.texture
the issue is that the depth buffer not working correctly
the axesHelper behind the boxGeometry is appearing which should not be