They share some of it with other scientists, but not everything. If the government is funding your research project, for example, there may be strings attached.
Many Chinese students are legitimately trying to obtain a western education to improve their future, with the goal often a new life in a western country. But many others are operatives for the Chinese government, seeking to steal information. When many Chinese-Canadians protested in support of the HK democracy activists, they were hounded by Chinese “students” aggressively promoting the Chi-com party line. Very hard to separate the friends from the foes.