It is deeply invasive and should be blocked.
It works like this. You go to a store and buy, say, a sexual wellness product. You then get targeted with ads online (search result ads, facebook ads, news media ads, amazon sponsored results etc) for the same product, or something related (let's say something embarrassing that you might not want other people to see). Other users on your same network or IP may also be re-targeted with the same ads.
Credit card data tracking is a levelling up of surveillance capitalism. It is deeply intrusive. Not all card providers participate, but it is a significant source of revenue for them [1]
[1] https://www.fastcompany.com/90490923/credit-card-companies-a...
[Edit: Removed specific reference to a medication as it likely triggered anti-spam]