Hmmmmm.. YUP.. Agreed w/ above..
I'd start with the LEAST Caustic Solution first.. and maybe even 'mild soap' and a damp cloth to begin.. ** and DO Not rub too hard in any one particular direction, the MBP finish is Anodized, and will surely show what you abuse it with, no matter how gently you think you are being with it.. 😱
Think of the Sticker and its 'Leftover Shadow' as being a Tan-line.. the area around it has Aged with use, and under it has not. In time, it will quite likely catch up, depending upon what sort of life it has lived!! 😎