A section of the translucent sheet, covering the glass, double doors of one the hotel's service entrances, that was apparently cut out and replaced by four separate strips, of a material possessing a higher degree of translucence...

 

(For comparison and further clarification, please, refer to my preceding post.)

 

P.S.: The fly - an added bonus - I had only noticed after editing the photo on my much larger, iMac screen.