Make Firefox Private Again

Since the makers of Firefox unfortunately turned on private attribution by default (why? Mozilla, why?), the internet answers with an easy and automated way to turn it off again (at least on Unix style systems).

And here in short how you can do that within Firefox itself (and also verify that the automatic way described above succeeded):

Open Firefox’s settings page at about:preferences
In the Privacy & Security panel, find the Website Advertising Preferences section.
Uncheck the box labeled Allow websites to perform privacy-preserving ad measurement.