Domoticz

I have had a CO2 meter MH-Z19B for more than 1 year.
The strange thing is that exactly 1 year ago on 28-5-2019 the lowest value measured in the graph is 399 ppm.
Today the latter value is also 399 ppm.
According to https://www.co2.earth/ and climate alarmists, the CO2 value of the earth is increasing.
The values ​​(albeit from May 26) of https://www.co2.earth/ are now
May. 26, 2019: 414.06 ppm and May. 26, 2020: 417.70 ppm
Here the values ​​now increase by more than 3 ppm in a year, but not with my meter.

Is my CO2 meter now degenerating?

B.T.W. A pitty that domoticz does not hold more then 1 year of data like electricity and gas.

We are working with Co2 Meters a lot and recently also started using domoticz.
The problem is that your sensors accuracy range is just too broad. Its a very unreliable sensor. We actually calibrate them using the "fresh" outside air.
If you want to check the findings of researchers you can 100% redo the experiments that they do. Thats called teh scientific method. but you need the right equipment and know how to use it.
If you are serious about this issue, contact a nearby university with your questions. If you ask nicely (these are busy people) someone in the metereoligcal department will show you how they measured the value. Maybe even show you live data coming in.
This person would also be suited to explain why our sensors costs xxx$ and theirs xxxxx$. the reason is mostly the accuracy.