Earlier quoted context omitted.
It's likely they have an ML "recommender" model that was built off of your history, but doesn't actually store the history nor is it reverse engineer-able. Once you hit a certain threshold of activity or time duration, the model will probably rebuild.
This is a big reason I view the new “we’ll automatically delete your data!” Crap as disingenuous at best. They’ve already learned everything from the data in a few hours, it’s useless after that anyhow.
E.g. a sexual photo retrieved from a private social media album is no threat to your reputation when it’s been assumed into some machine learning model for detecting sexual photos, but it’s certainly a threat if a future data leak allows your enemies to get the actual .PNG or .JPG and send it to the news media or your loved ones. Knowing that the photo can actually be deleted is valuable in this case and I’m sure there are many other similar ones that could be listed.