Note that US has set the precedence. US persons travelling to China, HK and Macau will be fair game and this can serve as the justification.
No formal charges has been made. Only allegations that she faces charges. BIGLY SAD
It's much worse that that.
The US set a precedent for extradition in a third country.
Imagine if China passes a domestic law which makes trading with Taiwan a crime.
Now China can extradite US executives if they travel to Canada or anywhere else in the world like Australia, Europe, Japan, Korea, etc
And for that matter, every other country in the world can apply their own laws globally.
It will make for an ugly ugly world.