Where can I get custom lists for Opera's built-in blocker?

Question

Opera

For example, if I want to teach the built-in blocker to block Yandex ads, where can I get a filter?

Answer 1

block Yandex ads

Yandex is a partner of the Russian Opera - many of their services are built into it, so you have to configure them for others (well, at least there is such an opportunity), these settings are periodically reset. It is clear that Opera will never block Yandex, even if you make a custom list.

Answer 2

built-in blocker to teach how to block Yandex ads

I wrote you a comment, and only now realized.
I used uBlock Origin in Opera due to the fact that the built-in blocker is disabled on a number of partner sites.
Google and Yandex are among them. So with a high probability you will not be able to block Yandex.advertising, at least on the sites of Yandex itself. Maybe on others too, but I don’t remember it anymore - I need to double-check.
So, most likely, you also need to start by installing ublock: https://addons.opera.com/en/extensions/details/ublock/