https://www.w3schools.com/php/phptryit.asp?filename=tryphp_filter_adv3 is a tutorial example. It attempts to validate what appears to be a valid URL but claims it is not.
I see this forum gets little use, so has the language changed since the example was created, is there a mistake in the example, or is the problem on my end in the browser?
I am using the latest FireFox browser under Windows 10.