China does not recognize the international tribunal’s ruling.
The international tribunal did not have the standing to make the ruling that it did. China's claim to the ECS predates the UN and the international court, the UN (lead by the USA) stole control over the sea and retroactively legalized their theft while China was fighting a civil war.
For the record, Taiwan claims precisely the same thing. But they're a US-backed puppet regime so they can't move against the US the way that the PRC can.
If you're not comfortable with totally eliminating extreme poverty, taking the largest steps of any country on the planet to combat climate change, and having a democratic government that exercises control over the capitalists rather than the other way around, then your comfort is not something worth caring about.