actually.. i dont know if id call this image problem a "bug" so much as an "incompatibility". librewolf and mull, and presumably other forks, specifically and intentionally disable the browser feature sharkey uses to handle uploads, and sharkey provides the "keep original image" toggle to get around it.

i think it could be implemented more gracefully, keeping the original image by default until the user chooses to edit, which would limit the scope of the problem. but that has clear tradeoffs, because the conversion to a canvas object allows clientside compression and optimization. i dont know if sharkey does that, but if they make it a canvas object they might as well.

at the very least there must be some exception that can be caught to automatically toggle keep original image or warn the user that canvas is borked or something.