Skin got noticeably better during DF but dandruff would return after a week or so post-refeeding. Only saw consistent improvement until after switching to a high-fat (low seed oil) keto diet.
DF is great for skin in my experience, but for long term improvement, diet seems more of a factor, at least for me. And I do realize appropriate diet is very different across the population. For me it was ensuring a higher intake of animal or dairy fats and cutting back on specific seed oils (not all).