Doubleclick cookie notice: "Used by Google DoubleClick to register and report the website user's actions after viewing or clicking one of the advertiser's ads with the purpose of measuring the efficacy of an ad and to present targeted ads to the user."
Facebook cookie notice: "Used by Facebook to deliver a series of advertisement products such as real time bidding from third party advertisers."
These descriptions fail to mention that the collected data will be combined with information from thousands of other websites you visit which allows to create sophisticated user profiles. From these profiles, you can infer things like gender, age, socio-economic status, interests, or hobbies with relatively high accuracy. Even if you asked them, Google and Facebook couldn't tell which hidden categories their machine learning models can discover.
Edit: and yes, I just checked and it looks like Cookiebot.