It's important to understand that constant propaganda leaves layers of bias, not just a clean single sheet. You can learn more and unlearn more bias, but you yourself will likely not see that you still have that bias without doing a lot of self-crit.
I was raised in a conservative family, so my journey to Marxism has been a lengthy process. Nearly fell down the alt-right pipeline, then was a liberal, a socdem, a demsoc, an Anarchist, and now a Communist.
The biggest driving factors of these shifts have been peeling off these layers of bias, which was usually a combination of touching grass, sympathizing with marginalized people, and reading theory. YouTube videos were helpful at first, and now actually reading Marx and Marxists are my primary ways of engaging with theory. Lemmy has also been instrumental, talking with leftists of all kinds.
Everyone's journey is different, but theory and grass touching I think are universal bias-peelers.