If brainwashing/indoctrination was actually a thing and successful, logically it would have to be done by the opponents of the perceived indoctrination. Because the indoctrinating side would want you to disregard the truth as brainwashing.

The reality is pretty much everyone is lacking in critical thinking skills regardless of education level. We spend few classes over our lifetimes learning critical thinking if lucky (usually actual school courses are more about memorizing some information rather than thinking), the rest is being bombarded with emotion-laden misinformation by corporate and social media that's more incentivized to get our attention by any means necessary than to actually inform us.