Earlier quoted context omitted.
To explain how this happens will take several pages of notes on the complexities of ad serving that are the exact opposite of "not clever enough". A summary is that your adblocking may have an impact on syncing stats, your purchases are not unique enough to matter for that category, serving some ad is better than serving no ad, and it maybe better to show you that impression however worthless than to bother with some…
Actually before I was ad blocking, two large local electronics stores did the same stupidity. I bought some expensive electronic toy, then was followed for a week by google ads for the exact same electronic toy. Which i had just bought. And was expensive enough to not buy another. And the ads were for the EXACT SAME STORE i had just bought it from. I repeat, that was before I began blocking ads. For a while I was on…
It's very hard to remove you from that segment on a consolidated check out page that would need some backend mapping with the products you bought and the removal pixels for each product and ad network, along with lots of other issues. It's just not that simple as you may think to keep things in sync.