Power corrupts. Corrupt people would lose power if their corruption is exposed. People speaking out about corruption imperil those in power. It's a pretty simple relationship.
The linked video is instructive on the corruption in the PRC and WHO. The actions of China and the U.N. discussed in the video appear to be directed more toward maintaining their power / authority than solving a public health crisis. This is an anecdote about the tension between the free flow of information and the accumulation / retention of power. I commend her courage in speaking out and pray for her safety.
More generally, those who want to stifle speech are serving the ends of the powerful (and corrupt). Limitations on free speech, whether social media censorship, "hate speech" laws or the "cancel culture" don't serve the minority communities or dispossessed. They serve the interests of those in power. "Shut up" is an argument made from a position of power, not from the powerless.
Consider the attacks on J.K. Rowling. She expressed an opinion that 5 years ago would not have resulted in any response. The powerful interests trying to "cancel" her are not engaging in a substantive argument / debate. They are exercising influence to shut her up. You can agree or disagree substantively with with Ms. Rowling said. That's fine. Engage in civil debate. But depriving her of the opportunity to voice her opinion is Orwellian and, frankly, evil.
Freedom of speech includes the freedom not to speak. The "silence is violence" movement to compel only approved speech is no less a violation of free speech than other types of censorship.
The market place of ideas freely exchanged is a means of exposing truth and a check on the actions and corruption of the powerful, whether or not in government. A market has a way of rejecting speech without value. We should be concerned with persons or entities whose contribution to the market is suppressing the speech of those with whom they disagree. We should express our concern as needed by calling out those who co-opt and silence the speech of others.