How did the site block the ability to open links in a new tab?

Question

Google Chrome

How did the site block the ability to open links in a new tab? Allegedly because of the adblock, but it’s clear that it’s not because of it, it’s interesting how it works, I’m just doing web development and I thought that I know how the browser works, but I can’t get to the bottom of it.

spoiler

https://dota2.com/adwarning/