Here, according to C.S. Lewis, is what value subjectivism is about.
"We appear to be saying something very important about something: and actually we are only saying something about our own feelings."
He writes that in The Abolition of Man.
Philosopher Francis Beckwith writes:
"Value subjectivism is a universal acid that cannot be constrained to judgments about the goodness or beauty of the natural world. If it is true, the theory must extend to human nature as well. We therefore, cannot say what is intrinsically good for human beings, since goodness, like beauty, is solely in the eye of the beholder. This means that there is no natural moral law that may guide society in the development of its laws and customs. Truth yields to power and to the value subjectivity of those who wield it. That leaves politics and law in the hands of unaccountable elites who saddle humanity with their vision of “goodness.” Under this scenario, generations of human beings remain in bondage to the capricious whims of the powerful elites. This, Lewis maintains, is the abolition of man." (Here.)
I'm re-reading Abolition.
The definitive book on Abolition is by Michael Ward, After Humanity: A Guide to C. S. Lewis's The Abolition of Man.