https://validator.w3.org/check?uri=referer checks random page totally unrelated to the actual referring page

[YvesMarcoux]

trafficstars

https://validator.w3.org/check?uri=referer does not check the referring page, but a random page from the web, totally unrelated to the referring page, for example http://www.robothumb.com/stats.html or http://www.wpu.edu.ph/ , while the referring page is in the .ca TLD.

The problem can be reproduced consistently (although the random page varies from time to time) with numerous different referring pages and with all browsers at hand (Firefox, Chrome, Edge).

It is not a browser-related referring-URI shortening or hiding problem that can be solved by browser configuration. The URL of the page actually checked is never sent by the browser, it appears to be already sitting in the validator as a result of a previous validation request.