So everybody here doing the "mistake" thing as if there's the slightest sign that this was on purpose. Despite their explaination is 100% consistent - the only comment I'd expect from a technical knowledgable person is "yeah that's the kind of mistake that happens when you need to juggle a shitton of load in a global customer base."
Having geofencing in their routing algorithms is state of the art, and probably more advanced than most other services.
They accidentally whitelisted Chinese servers for non-Chinese users. What does that have to do with anything technical or scaling? It'd be a scaling mistake if the whitelists didn't exist because they thought Chinese servers would never be chosen because of the distance, but they already knew that could happen.
Because the Great Firewall operates as a blacklist and is only intended to prevent commoners from learning censored information.
If Zoom meetings where anyone can join became a popular source of unfiltered news, they'd either ban Zoom or require that a two-class system is set up to prevent ordinary Chinese users from using Zoom to communicate internationally, similarly to how Douyin (within China) and Tiktok (everywhere else) are two separate silos.
But people from other countries connecting to servers in China is not something the Great Firewall tries to interfere with.
From my experience it's not just a blacklist, any non-blessed traffic is slowed down to a crawl (on the order of double digit kbps). This also applies to getting content from China.
(that said, it's pretty reasonable to assume Zoom is not throttled given how important it is in the buisness world)
Rent a vps on alibaba cloud in China, try to scp a file. Last time I tried it went from slow, to really slow to a complete stop. The file was not even big...
Having geofencing in their routing algorithms is state of the art, and probably more advanced than most other services.