Same thing with kitchen appliances, but not limited to Facebook. I'm not going to buy another refrigerator for at least 10 years, but still I'm treated as Mr Fridge.
Honestly this might be a good thing, it seems to show that ad networks don't have or at least don't provide your actual purchase history to the ad space buyers because given that info they probably wouldn't be spamming someone who just bought a $thing with ads for $thing_but_from_us. As annoying as it is it's probably better than the alternative of ubiquitous access to your purchase history.
Yup, I get "buy it again" prompts on nearly all of my recent purchases, even when they are all durable goods that don't expire or require restocking, like say a tablet case.
Hmmm, that's really weird. It's probably an edge case that would be complicated to change in that case (never underestimate the power of inertia, especially in ML systems).