Do you feel that the body has many folding bike safety?
After a period of time, folding will not affect its security?

From what I read it might depend on the quality of the folding joint. One recent thread talks about a Dahon lock that some consider dangerous.

https://www.bikeforums.net/folding-bi...-mezzo-d9.html

I would consider looking into

Dragon

The Dragon is our halo product with a full carbon frame, articulated hinge, and a 9-speed Shimano Sora derailleur.

The beauty of the Dragon goes beyond its carbon-fiber frame and light weight. The Dragon rides, and handles, like the well-balanced machine that it is. The articulated hinge provides two pivot points and allows the main tube to be perfectly smooth thanks to the recessed release lever; this design also increases the strength and rigidity of the frame.

The Sora gear set outpaces the competition and provides crisp shifts and reliable performance.

origamibicycles.com/product/dragon/


Also

formosastars

Fast Formosa Runing Stars 3-Speed Folding bike - Video

the hinge on the steerer went on mine first