Does this actually work correctly for anyone? Got wrong results for Firefox and Chrome on Linux (it warns that Chrome probably won't work).

I glanced through the source[0] and my about:config and I noticed I have the dom.block_external_protocol_in_iframes setting enabled. Looks like this could be the mechanism they use? I don't remember enabling it manually.

Otherwise, it could be my tiling window manager messing with detection.

[0]: https://github.com/fingerprintjs/external-protocol-flooding/...