Ironically, Republicans do not oppose indoctrination of schoolchildren. They have been enforcing it for decades to teach white superiority. What they object to and now call indoctrination is the teaching of the history of Black people and other minorities and how white people legally and illegally tried to destroy their economic prospects. And yes, we do have systemic racism in the US. It is supported by attitudes of those who believe that the US should follow only the white traditional way of life.

Opinion | Who’s Afraid of Black History? -
https://www.nytimes.com/2023/02/17/opinion/desantis-florida-african-american-studies-black-history.html