What is the reason for the redirect on one provider?

Question

Browsers

Good afternoon! There is one .rf client domain. So, when switching to it from a home provider (Rostelecom), from any device, a redirect occurs to various resources with pron. If you use VPN extensions in any browser or TOR, then the site opens normally. The acc at the domain registrar is not hacked, there are no redirects set there, the hosting just created it. I scanned my devices with antiviruses.
UPD: a friend with the same provider confirmed. From Rostelecom - pron, from mob. Ineta - everything is ok.
I vaguely imagine where to even dig here. Maybe someone can shed some light...

Answer 1

The question, of course, is old, but I myself encountered such a problem. I think the information will help those who come here from Google.
TLDR: Rostelecom interferes with traffic by replacing js scripts downloaded over an insecure connection.
More details:
https://habr.com/ru/post/489528/
https://www.opennet.ru/opennews/art.shtml?num=52444