La Roche-Posay Vitamin C Serum Leaving Stains on Pillow and Clothes

I bought the La Roche-Posay Vitamin C dark spot serum from a pharmacy. I use it at night. I go to bed about an hour after applying it, but it still leaves stains on my pillow and pajamas. The stains do not come out — even stain removers haven’t worked. My pajamas and pillowcases are ruined. I don’t understand why this is happening or what I’m supposed to do. I follow the storage instructions, I bought it from a reliable pharmacy, and it has only been about a month since I purchased it.

I’m waiting for an explanation and I request that my inconvenience be resolved.