Why does it automatically change the phone number on the site?

Question

JavaScript

When copying the site, I found that as soon as the page is loaded, ALL phone numbers on the page change to another one that I don't need. I noticed that this disappears if JavaScript is disabled in the browser. But this does not solve the general problem. What could be causing this bug?
The archive itself with files (maybe someone will try to raise it on their server):
https://yadi.sk/d/AGdeISy47sP0Mg
Video of what is happening:
https://youtu.be/Uc4qjj9qLws

Answer 1

I 'm too lazy to watch the archive, but according to the video - most likely, this is not a bug, but dynamic call tracking .
Many services provide similar things, I took the first article that came across from Google - you should not consider it a reference performance. :)