The Shanghai police has a unique role in China and abroad. For example the Shanghai police is tasked with spreading pro-CCP propaganda globally on platforms like twitter and Facebook.
There was an HN post about this a few months ago:
https://news.ycombinator.com/item?id=29654137
Someone posted a comment explaining a little more about Shanghai's special relationship with the CCP/PLA:
>Shanghai is a city with a unique role in the progression of the CCP and its global efforts. Also PLA Unit 61398 is in Pudong, the shanghai district mentioned in the article. Overall there's a lot of CCP/PLA-adjacent tech talent in the area, and of course the local police still ultimately report to the CCP.