Much more likely an explicit retargeting ad network that doesn't realise they already bought it.
Retargeting has been a thing for like 15 plus years now. Visit website for knives, ad network tracking cookie notes that down, same ad network later serves you ads for the same knives. Or some convoluted data sharing network that has the same outcome these days.
It's not much more likely. People don't realize but demographic targeting works really well. When you are a certain age, certain gender, living in a certain area, with a few other inferred characteristics, you're very likely to be talking about, thinking about, and buying a small set of product types