I've seen this firsthand - a family member ordered what they thought was a legitimate skincare line from a major marketplace and it turned out to have hydroquinone at levels way higher than allowed in most places. The product looked completely professional, had good reviews, and came from what seemed like an established seller. When we actually looked up the ingredients, it became clear nobody was checking what was actually in these listings.
The problem is that big shopping platforms rely on seller self-reporting and user complaints to catch this stuff, which means harmful products can sit up there for weeks or months before getting flagged. Sellers operating from outside strict regulatory zones can list things that would never pass inspection locally. The visibility of "sold by [major retailer]" gives people false confidence, even when the actual third-party seller has minimal oversight.
If you're considering any skin-lightening product, the safest move is going through a dermatologist or buying directly from pharmaceutical companies' official websites. Even then, check what's actually approved in your country - something legal in one place might be banned in another for good reason. The ingredient lists on marketplace listings are often incomplete or outright fake, so a nice product page isn't worth risking your skin over.