via Martin Brinkmann, writing as he does on gHacks.net, details a specific attribute to be included in the upcoming Firefox 67 release (slated for May 14th, 2019 (the date provided is somewhat 'fluid', as delays may require a reset on the claimed release date). At any rate, the specific release wil include anti-fingerprinting technology.
"Fingerprinting refers to using data provided by the browser, e.g. automatically or by running certain scripts, to profile users. One of the appeals that fingerprinting has is that it does not require access to local storage and that some techniques work across browsers." - via Martin Brinkmann, writing on his gHacks.net