This doesn't seem to work very well. Want a better scriptless cross-site tracking mechanism? Check out https://xsid2-demo.glitch.me and https://xsid2-demo.easrng.net and note how they both get the same id.
There was an initial screen, then a redirect to another page containing the text below, and appearing to depend upon JS being enabled.
"Waking up
To keep Glitch fast for everyone, inactive projects go to sleep and wake up on request."
That redirect is different for the two initial URLs, but is of the form:
https://xsid2.glitch.me/https%3A%2F%2Fxsid2-demo.glitch.me%2Fcb%2FHASH
I'm using Firefox, with uMatrix having scripts and css disabled by default, but 1st party cookies enabled.
Reloading each tab then gave two different numbers, 7eb6 and 6f83
Subsequent reloads did not change again.
Loading the sites in to two more tabs, gave yet a different pair of numbers (1934 and 1667), reloads of those tabs yeilded another pair (b308 and 3df8)
Edit: it looks like this happens when the sites have gone down and are being restarted on load. I'll move them to my VPS, that should fix it.
On the glitch website, I get f9703...
On the easrng website, I get 8ecd6...
Without digging too deep into what your websites are doing, I did notice that they're trying to set / read cookies, which is a) being blocked by uMatrix in general, and b) perhaps being blocked by me having configured FF to block third-party cookies in particular.