Oh, this is hilarious.
A month ago, after hearing that Firefox was becoming increasingly skeevy over AI junk in their software, I turned off every data collection option for their organization.
That automatically disabled "Allow websites to perform privacy-preserving ad measurement" which is the setting for turning off Firefox's privacy-preserving attribution feature, which people now suspect is a kind of in-house spyware.
Go me, I guess.
https://noyb.eu/en/firefox-tracks-you-privacy-preserving-feature