My apologies to the Bugzilla team for wasting their time holding my hand on this one. Would have honestly never noticed the little “HTML5” info icon to the left of the URL bar though without their help.
Surely this is a user experience that could be improved, no? Awesome feature but confusing solution.
The resist fingerprinting mode scrambles canvas read out to prevent sites from using it to create a fingerprint. Because of that, any site that needs to read the canvas back for legitimate purposes will also receive scrambled data. You get more privacy for the minor inconvenience of having to manually allow canvas usage for the sites that actually need it.
And very few sites actually need it.
On librewolf I just get a popup asking to allow canvas
A popup sounds like an annoyance you must deal with on every webpage. Not just the ones that use the canvas for useful things
Canvas is rarely on a web page or at least it rarely affects me