The Facebook Pixel is one of the most used services on websites. It was launched in 2015 (here’s the link to the announcement), and the announcement made it clear back then what it was all about:
[…] a new way to report and optimize for conversions, build audiences and get rich insights about how people use your website.
In fact, the Pixel is similar to Google Analytics in the way it works:
Ultimately, the goal of the Facebook Pixel is to optimize the performance of advertising campaigns. The pixel does everything that is not at all welcome from a data protection point of view – it sets cookies, transfers data to an unsafe third state (from a GDPR perspective) and is used for profiling. Its use is therefore not permitted without consent.
If you want to verify for sure whether a website uses the Facebook Pixel, and whether it is loaded with or without user consent, then simply proceed as follows:
www.facebook.com/tr/?id=....
This network request is proof that the Facebook Pixel has been loaded. Since you haven’t interacted with the consent tool yet (you can see it’s visible in the screenshot), it’s obviously loaded without consent in this case.
There is more evidence we can check out.
The cookie with the name _fbp is set by the Facebook Pixel and is used to recognize returning visitors in order to further enrich the user profile.