We shouldn't punish China for simply having the virus. That could happen to anyone. But lying about it on the world stage for months, imprisoning whistleblower doctors, etc is reprehensible behavior.
China misled WHO into thinking the virus wasn't contagious up until Jan 20. On Jan 14th, WHO (https://twitter.com/WHO/status/1217043229427761152) said the virus wasn't contagious on twitter.
China arrested scientist whistleblowers. https://www.businessinsider.com/china-coronavirus-whistleblo...
To top it all off, China attempted to blame the united states for it. https://qz.com/1817736/china-fuels-coronavirus-conspiracy-th...
The Atlantic has a thorough article as well. https://www.theatlantic.com/ideas/archive/2020/03/china-trol...
As far as we know it was identified as a novel pathogen on the 26th December. Its actually hard to know where to collect the sample from, and if you don't know what you're looking for, its extremely easy to miss. You can't just put a virus under a microscope. Its not unreasonable to assume that they didn't have any confirmation for a couple of weeks that the virus they sequenced was the exact same virus for all of the other cases. You need to develop a fool-proof protocol for a diagnostic test that has minimal false-negatives. No easy task to do in 2 weeks, etc, etc...