I am not sure where you are shopping, but I think there are shops and selling platforms on there where a lot of things are sold as "vintage" that are not. There are unfortunately also sellers who do not seem to understand the meaning of vintage. That's why it's important to learn about how to identify vintage if you really want to get into it. Like I've said before, there are many clues in the garment - the shape and style, how it was made, the material, the care labels, the information on where it was made or information about the brand. And fashion history too, knowing what was in fashion when. And if a seller isn't giving enough information online, then one has to ask more questions.