https://spacenews.com/chinese-spacecraft-prepare-for-orbital-refueling-test-as-us-surveillance-sats-lurk-nearby/
>Shijian-21, likely designed with such tests in mind, makes a good target for China’s first on-orbit refueling test in GEO. The mission appears set on demonstrating capabilities for maintaining and prolonging the operational lifespan of satellites already in orbit. Such capabilities can reduce costs and improve sustainability in space operations, while also reducing debris.