We could never actually reference a color style in a gradient, but I could pick colors from my Styles library in the bottom swatch area of the gradient editor panel. Again, this wasn’t a true Style’s reference, but it allowed me to grab the color/hex quickly for the gradient.
With the recent release of variables this was removed. Libraries was added to the top of the editor, but this applies a style/variable to the fill and completely overrides the gradient.
The only way to pull this off now is to go into a variable/style definition, copy the hex and the paste it into the gradient. Alternatively, apply it to the fill, break the reference, copy, and undo. Then repeat for other colors in the gradient.
Ultimately I’m hoping we can reference variables in gradients, but regardless of that being able to quickly grab the color (even without being bound) was extremely helpful. Making/editing gradients now is extremely cumbersome.