In case you're using Firefox on mobile - so myself and like four others - disabling Firefox' new Facebook data collection feature is quite a bit harder than on desktop, but it can be done:
Go to 'chrome://geckoview/content/config.xhtml'
Use the search field to find the entry for 'about:config' and enable it
Go to 'about:config'
Search for 'dom.private-attribution.submission.enabled' and set it to false
Done.
@datafuzz @thomholwerda try to search for aboutConfig without the colon