[rasz]

> Unfortunately from our end it's also impossible to tell what canvases are being used for.

you mean trivial, right? calling getImageData toBlob toDataURL means fingerprinting.

[willbudd]

I guess it didn't occur to you that retrieving and setting image data with getImageData()/putImageData() actually turn out to be indispensable features when generating complex multi-layer canvases. Your trivial heuristic would flag a lot of false positives.