Incomprehensible characters of the source code, what is it?

Question

HTML

Tell me how the sites display strange source code from incomprehensible characters? Through online page source code viewers show unreadable characters. And all the ones I've tried. But the normal browser opens normally. I'm facing for the first time.
An example of such a site is a recently moved torrent kick es to the kat domain dot cr. Try opening it with curl or phantomjs/casperjs and you'll get characters back. Changing the encoding of the received code does not help. In meta kick es it is written that this is utf-8, but this does not change anything. There is a suspicion that this is related to https. Not?
Online viewing for an example - www.bertal.ru/index.php?a2132237/https://kat.cr#h or try any other.
Question: what is it? why? and how to get readable source code?

Answer 1

Press F12, look at the headers, and then go to php.net and read about gzip.