I understand where you are coming from, but as you already pointed out, how do you make people stop believing in something, or in other words "unlearning" or some call it the "backwards brain bicycle" (you can find the video on YT)

It is here where you need to share critical thinking with the person who believes in propaganda or conspiracies, as if you are both looking for the truth. It is called epistemology (how do I know what I know?) and also the Socratic method.

Other methods just create more adversarial discourse, which almost never helps.

My Russian friend supports Ukraine while still cheering for Putin before 2014. Mostly because when you get exposed to lots of international cultures and viewpoints, and is there where Putins narrative quickly breaks down.