They're not learning, they're being indoctrinated. They won't be told of any of the downsides or failures of Xi's ideology.

Since it is one of the compulsory subjects throughout my secondary school and highschool, I had the opportunity to read all the text books. Of course, the teachers are not great (most good teachers are teaching stem subjects), most students won't pay attention to the texts, there are a lot good information in the text book. I don't remember most of them, but I do remember text made me want to study hard and go to college.

You made a jump there but didn’t notice it. Xi jinping thought = ideology and government. There’s no class on Joe Biden thought taught to 6 year olds.

This is not true. 6 year old is year 1 in Chinese primary school. Apparently it is going to be taught at year 3, year 5 in primary school, year 2 in secondary school and year 1 in high school.

I haven't read the text, my assumption is that it would be similar to Mao's, Deng's and Jiang's Thought. Why I consider it is about the government? For example, Deng's thought would set modernization as the priority for country's development. Xi's thought would set new priority. It is just how Chinese government works.