Yellow stains from suction cups shower walls

Hi There

Hoping someone can help with this. We placed several baskets and a small suction mirror on our shower walls which are white platic.
Upon removing these items to clean the walls and shower tub the suction cups have left a perfect yellow circle behind which I cannot remove.

I have tired neat bleach, hydrogen peroxide, soft scrub, scrubbing bubbles, nothing seems to work. Even the area where the shower curtain drapped on to the tub floor has gone a litle off colour too, it is as if the area where no light of air has circulated the plastic has discoloured.

Can anyone tell me how to get these yellow stains off please.

Thanks for any ideas I am sure many of you must have had the same issue.

Julea