@thknker
You could have a look at the last few posts on this thread below to check the size of your hosts file to help to confirm it is set up okay.
https://forums.ubports.com/topic/7377/why-uadblock-currently-no-longer-works/22
I think you should be able to see the hosts file from 'file explorer' in /mydevice/etc/, it should be a few MB in size.

@keneda Call app does not help, the phone would still start ringing. You need to catch this in a lower stack part, since the phone should stay silent during a blocked call right?

On a mobile phone using mobile data represents an extra expense for ads, web pages that are reloaded, especially, online newspapers ... The best thing to do is, edit the "hosts" file and add, as the previous partner the web address to the resolution of domain name 127.0.0.1 which is the internal network card and will not load anything at all, and who wants to support a web page because it is hard for the creator of it to do what he does, you can click and put it on the white list as advocatux says, but you don't bother to read, you don't pay attention, people just want to be heard but they don't listen, anyway. HAPPY YEAR 2020. (Google Traslator, Hello of Spain) ;).