Lots of people on HN (and in the tech industry more broadly) live in China or have family in China. You can ask anyone you know who lives in China or who has family/friends in China what the situation has been like over the last year. Public spaces like restaurants and theaters have been open, nobody is coming down with CoVID-19, and the hospitals aren't overflowing.

This would simply be impossible if there were community spread of the virus inside China. With open restaurants, theaters, etc., the virus would spread like wildfire in China's dense cities, and everyone would know about it. The strict lockdowns in early 2020 worked to bring cases very near zero, and they were followed up with mass testing campaigns (for example, nearly all 11 million residents of Wuhan were tested in June 2020) to find the last few infections.[1,2]

The common reaction among many people, to deny that China eliminated SARS-CoV-2 within its borders, simply isn't tenable.

1. "Post-lockdown SARS-CoV-2 nucleic acid screening in nearly ten million residents of Wuhan, China": https://www.nature.com/articles/s41467-020-19802-w

2. "Comprehensive large-scale nucleic acid–testing strategies support China’s sustained containment of COVID-19": https://www.nature.com/articles/s41591-021-01308-7