[zodiac]

You could examine network traffic to confirm that not enough data is sent to reconstitute the picture

[the8472]

They could save it indexedb or localstorage and send it later. So now you have three things to inspect. They could even shunt it to a different domain within the browser through iframes and messaging. Now you have another thing to watch. There aren't even any devtools to watch that.

The cheese is full of holes.

[icebraining]

You'd have to check every single time, since the code can change at any time.