Custom filter rules for the native adblocker

What does your feature entail? What is it for? How will it affect existing workflows or user experience?

In the current native adblocker settings you can only manage custom filter lists by urls. If you want to write a custom rule yourself, you actually have to host the rules file somewhere. It would be nice if you could write custom rules without going through all that.

What are the exact ways that you see a user using your proposed feature? Please go into as much detail as possible, and provide examples of how other browsers/apps implement this feature, if applicable. If your feature suggestion adds on to an existing feature, how would it work into it to extend its usefulness?

A simple textarea where you can write one rule per line would do. Similar to how uBlock Origin does it. You might also want to validate that the rules are valid and highlight errors.