not PBR, transparent plastic is a version of a Cynicat Pro-Glass/fake refractive node, that avoids fireflies. Due to this, the refractive caustics are turned off. The main rendering was done with a 1024x1024 hdr from Greg Zaal which is not included but you can get it from https://hdrihaven.com/index.php. The second image uses two light-planes and filmic blender. The darkest image uses standard blender colormanagement
this is amazing ;}