What was the real reason for closing the country to the outside world in Ming and Qing Dynasties?

What I want to explain here is that the Ming Dynasty implemented the policy of sea ban, and the Qing Dynasty was a closed-door dynasty.

In the Ming dynasty, people were forbidden to go to sea for trade activities, but there were no official trade activities, such as Zheng He's voyages to the West and tributes from overseas countries. The Qing dynasty restricted people from going to sea for trade activities, and officials did not advocate foreign trade activities.

Reason:

Ming dynasty: the direct cause: preventing the harassment of coastal warlords and pirates, and the fundamental cause: reducing the economic burden and enabling farmers to concentrate on agricultural activities.

Qing dynasty: direct cause: preventing collusion between anti-Qing restoration forces and overseas forces, and fundamental cause: the product of feudal economy and self-sufficient small-scale peasant economy.