Light reactive
Not much of a carpenter but I have considerable boat refinish varnish exp.
Depending on the U.V. qualities of the wood and the resistance of the finish it's rather amazing what will change. I remember taking a piece of Cherry and taping a quarter on it and putting in the sun for one week, big difference in the darkening, this was when considering flooring for my residence.
I had a Prestige auto wood dash on three cars. They use a one and done epoxy coat which is rather thick and easily chipped near the edges of the instrument holes. All you can do to repair that happens is use nail polish.
A dash that came with my 3rd. Tiger was sold off as it had a Shelby signed glove box door and it had some noticeable color difference between the lower dash pad and the uninstalled glove box door.
What's the point here? protect it from the sun or get a finish with some U.V. resistance. Epoxy is not as good as the best old school marine varnish with U.V. inhibitors and some wood is more susceptible to darkening then others.