My perspective on what might contribute to this (perceived?) lack of open source contribution coming from China may partially be our (the US') fault. Everyone knows that open source has mostly shifted to being commercialized on the whole and therefore most of the development is done from 9-5. There is literally no intersection of normal business hours between the US and China, so synchronous communication is severely impeded. Obviously, many open source projects are excellent at working completely asynchronously. However, many are not and I think the commercialization trend of recent years has made it even more so a rarity. I've personally seen an uptake in video chat meetings that are sometimes not even recorded, so it's difficult for non-attendees to follow the project. One of the fantastic things I saw in the OpenStack community was a very intentional effort to schedule alternating meeting times to maximize time zone coverage of waking hours. (It was also in text, which made it easily archivable, searchable, and available to people with minimal bandwidth.)

I realize of course that open source development occurs outside of the US and I may be inflating my country's importance in the whole matter. Would love to hear from some non-US open source devs how their contribution experience with people from China compares.

Could you outline the cultural differences that make open-source work unpopular with Chinese?

It has more to do with economic conditions I believe. Here in India it's the same, most people get into software engineering because of easy availability of jobs and don't really care about Computer Science itself. So the concept of Open source feels alien to most engineers here, especially "working for free" when you have to struggle so much just to get a very basic salary.

Also who has time for side projects when you work in the 996 work culture.

I don't think this can be generalized for China. Plenty of companies in India, Japan and US have the same shitty culture too. Tesla, Space X, Apple are infamous for such workaholic cultures.

Products get cloned almost immediately once released in the Chinese domestic market, especially when there's a potential for them to make money. It's about keeping the IP as closely guarded as possible while attracting users.

Companies are very conscious of copying and they see open source as only facilitating that - the cons outweigh the pros. Tech savvy consumers don't appreciate that a company has open sourced some of its work because there's no culture of open source, and the act of open sourcing only allows competitors to rip something off easier. Why would they?

If there's no expectation of anyone contributing back, it makes sense.

OTOH I wonder how Vue.js, Cocos2D, echarts, etc even survive in this circumstances — these seem to have some contributors beside the original authors.

What a paradox!

Communist China doesn't want to share or work on Open Source, eh?

Probably because they understand the value of labor.