Gee, you think?
A distraction, of some type, at the very least.
You made me look and right now Marine Traffic shows THOUSANDS of ships at anchor around Shanghai. Zero chance that they’re doing anything in secret that has to do with moving anything by sea.
https://www.marinetraffic.com/en/ais/home/centerx:123.1/centery:31.1/zoom:7
The political purge then becomes the more likely reason for this crazy lockdown.