While the idea is nice theoretically, practically this addon isn't all that useful. Apps using canvas for legitimate reasons (i.e. WhatsApp web file upload, draw.io file export) will often have coloured tint (or sometimes it will just break the app completely) on them, which not only affects the web experience, but will also make you trackable. The addon does have a white-list function, but I haven't been able to get it to work. There's also an annoying notification that pops up on every webpage that tries to read your canvas hash and you can't actually disable it.