No, they want it back, they’ve had discussions during the cold war and since.

He’s saying they’re not doing anything about it now:

Complete restoration of China’s losses in that time is a driving narrative of the CCP, and today is largely focused on Taiwan.

However, Lai, who was elected president in January, noted that China also lost land to Russia during that period but was not making any effort to take it back

He’s saying Taiwan is just a noisy point to distract the domestic hardliners, which it is.

Russia is literally vulnerable now and 100% dependent on China, they could ask for it back if they wanted, but what China wants is the political issue.