They have a nice point there "What do negative counts of cases or deaths mean?". And this is a good starting point to see what's wrong with them.
Epidemiologic data usually has a date and some number as value. The main problem with WHO is that they don't use any epidemiological meaningful value for date. E.g. "Date of infection" or "Date of death" would be meaningful - they chose to use some strange reporting date instead - one that can be easily manipulated at will. And this first shows it's symptoms in negative death counts.
If you can get your hand on some real data - and compare - it's very obvious. If you can track some individual cases, you can see that sometimes date of reporting and date of death differs by 6 months. The way WHO does things obviously turns data to garbage.
Florida once was a good example. Florida published data like WHO for a long time. Numbers went up and down - and it looked chaotic - with measures supposedly changing things. And then one day they changed and started publishing data by date of death. Suddenly the chaos was gone, and everything followed strict mathematical epidemiologic functions. You could even write mathematical formulas with a single parameter for most of the curves - (That formula got flagged and censored here ASAP). Most likely people didn't like that the effects of measures were gone.
Sadly these topics here get censored too quickly to get any meaningful discussion going... If you're interested in real epidemiological data - you're mostly on your own.
The first thing to do with data is to get meaningful axis - then you can take care about the Y-Axis and figure out if data gathering was stable (it wasn't...) and then maybe correct for changes in data gathering.
Getting real epidemiological data is often a challenge - some states still make a big secret about meaningful numbers. But it exists and is available - there were enough official publications and leaks. If WHO was willing they could publish meaningful data instead.
WHO consistently failed for years to publish meaningful epidemiological data. They publish widely misleading data to be used by politicians. And they're not amateurs and they're not doing this by accident. The best thing would be to send those crooks to jail ASAP.
Another point to think about is that politics turned against them. This is something that doesn't happen for fun. Something like that takes years. People spent years writing literal books about what's wrong with WHO - tracking money and corruption... Even slow thinkers in politics meanwhile got the memo... but the slowest of the slow haven't got it, yet.
Is your data anywhere that I can read it and examine your specific analytical claims for myself or are you just going to bloviate about it