Oxidized vitamin C product

So I've just bought this vitamin c ampoule product, it contain 20% ascorbic acid and 2% niacinamide. But it turns out that the product has been oxidized, the color is change to be more darker. I still use this product for 2 days and there's no problem with my skin. But i still worried, Is this product ok if I keep using it? What do you think? Please give me some advice 🙏