Remove faint imprint of stickers from space grey macbook
The space grey coating is anodized and possibly dyed.
What your photo illustrates is differential weathering effects upon the aluminum surface. Where the stickers were is the original color - you actually are asking how to reverse the weathering or basically re-anodize or dye the layer of chemically modified aluminum alloy so that the exposed portions match the unchanged. An equivalent process would be to  somehow catch up the protected portions to match perfectly to the rest of the Mac.
Basically, you’re not likely to “fix” this just like tattoo removal in some cases isn’t able to restore the unpigmented condition of some skin types and ink combinations.
Back to the Mac - once you’ve used a solvent to remove the residue of any adhesive or remnants of vinyl or whatever other material you introduced, the actual oxidized layer may be permanently changed.