Laptop floor discolored yellow?

Hello today I cleaned my laptop and noticed that a spot had turned yellow. I do not know if that could be from the heat or from any food. I eat nothing yellow. The material is a matt plastic. Anyone have an idea how to get it out? Have tried it with sidolin but has brought nothing. Someone have any ideas without attacking or breaking the plastic?

It should work with citric acid.

Oil. Can also be normal WD40.

So I clean my PCs and solve paper glue. Best krichöl.

Before you do it you should check it on an insignificant spot on the device before, since the plastic is often a different mix of manufacturers. Mostly get rid of the stains with contact spray from manufacturer Nigrin.