I Found this paper while doing some research about yellowing of oils, it might be of interest to the forum, for the sake of understanding where this comes from for comonly used oil mediums. It's open access so anyone can download it from the editors.
For non-scientists artists here that don't have university access to research papers, in case you are interested in accessing the cited references (or other research papers that can be found in google scholar) for further reading, you can use the following website https://sci-hub.41610.org/
just paste the title, the doi or the url of an article there and it will give you access.
Turns out yellowing is not due to aging but to storage in dark conditions, exposition to light reverses the effect but is not recommended due to other detrimental effects. I would have thought the opposite.