Before Trump, people still believe USA is a great country even with so many flaws. Its still has a good reputation.Trump changed everything. He is not a bad leader, he has thoughts, but he cannot implement them with caution. And he destroyed USA's reputation, maybe forever.
Its hard to imaginy the greatest democracy' country, the president is manipulate the stock market, publicly, humiliating his friends country, or vaseel state. When the pro-USA people in china talks how great the USA is and China shoud learn from it, the comments is no longer agree anymore, most of them are mocking.and thats what the younger generation will grow up with, the mindset is: yes china is not perfect, but its way better than the shit countries like USA.
You can see the change in the numbers of graduates return to china after college, its used to be low, not its near or >90%.