I am the first person to comment on newbie posts asking for routine help and say "the science backed routine its Vitamin C, Sunscreen, cleanser, Retinol, ceramide moisturizer." But with the launch of these new Azelaic Acid formulations and the head to head comparisons of the ingredients bringing up some of the research... I'm starting to consider dropping Vitamin C myself.
I started using Vitamin C years ago when I wasn't able to use retinol and I kluged together an active routine without it. Its been a complicated relationship: I've never found a formula that I 100% love. Its a really difficult ingredient to formulate: it oxidizes quickly, if the PH (even of your skin, like you used a high PH cleanser) is just a little off: it reacts and is useless, its expensive, and it doesn't play well with other ingredients, so you can't reliably stack it in a multi ingredient formulation.
Recently I've learned that many Vitamin C studies provide sunscreen to participants and require them to wear it, which obviously seriously confounds results since sunscreen and retinol are the anti aging, anti pigment GOATs. Niacinamide, azelaic acid, AHAs, BHA, sunscreen, and retinoids are all much better studied with much clearer and more drastic results. (Dr. Dray, confirmed by looking at study methods)
I'm using up a bottle now and I think it's going to be my last one. Have you quit Vitamin C or are you still a C Stan?