https://www.theregister.co.uk/2019/11/21/ublock_origin_firefox_unblockable_tracker/

Developers working on open-source ad-blocker uBlock Origin have uncovered a mechanism for tracking web browsers around the internet that defies today's blocking techniques.

A method to block this so-called unblockable tracker has been developed by the team, though it only works in Firefox, leaving Chrome and possibly other browsers susceptible. This fix is now available to uBlock Origin users.