Yes, I recall that post, but I think the OP makes a fair point but has some truly unrealistic expectations of this device. That’s why these are so cheap; they are like BIC pens—when they stop working correctly, you throw them away.
BTW: The reason I got a chuckle out of his post was that he use the Thermopro hygrometer as a validator. Do you know how many of those $8 devices I have thrown away after failing within a year? if you take them apart, guess what you find? The same cheap sensor used in every other cheap hygrometer. I posted about that here with photos.
Whenever I open up a box of these cheap hygrometers, before I use them I run a simple salt-brine calibration test. None of these are accurate to more than ±3% in my experience. But we aren’t talking about laboratory-grade equipment either. One has to "Calibrate"
one’s expectations, doesn’t one?
Here’s a very simply search on YouTube, there are so many videos on how to check your hygrometer. All you need is table salt, water and a sealed container.
https://www.youtube.com/results?search_query=calibrating+hygrometer
BTW: I don’t even trust my Creality dryer sensor either which is why I keep a second sensor in the box just to keep the readings honest. The Creality Sensor is close enough or as the Chinese prefer to say, chà bù duō, which explains everything about products sourced in China from Chinese engineers.