Hi, developer of the site in question here. That popup exists to warn users that the fingerprinting protections, namely farbling, can cause minor amounts of visual noise to appear in their art. For a pixel art editor, this is not desired, and I received many bug reports about the behaviour, which lead to the popup pictured.

NeedCoolerShoes does not have any fingerprinting in place, and utilises only a privacy friendly analytics tool called counter.dev, where site analytics is public for all to see: https://counter.dev/dashboard.html?user=Moxvallix&token=d7TgWkme7Jo%3D