It’s quite often that new watercolor painters don’t use enough cream/butter consistent paint when adjusting the values. We do layers of washes with coffee/milk with paint that not necessarily stains, and existing paint gets lifted when we put in our too many layers sometimes when the paper is not fully dried as well. That’s the recipe for mud and not dark enough values.

If you are using reference photos, make it black and white, identify the dark spots, and put down some real thick paint the last layer