Dave;
If it is primarily d-Limonene citrus solvent, then there are several items that come into play.
Some products have changed the concentration of d-Limonene in the formulation.
Being a natural product, the growing conditions will have an effect on the color.
The color starts out clear and yellows slightly when exposed to air.
It will also affect the fragrance, but not to the same degree.
I would check it for solvent power first,
and then fragrance.
Larry