It's not capable of CO2 measurement, it only estimates CO2 levels based on measurements of VOCs. These estimated readings are garbage and have close to zero correlation with CO2 levels.
Unless I've got another source of VOCs around there should be at least some correlation with actual CO2 levels though? I don't have a reliable way of checking this, but the bottom end seemed well calibrated...outside air leads to a reading consistent with ambient co2
We tested a lot of VOC sensor modules and the estimated CO2 values they give is -in our experience- 80% of the time totally wrong. Also the absolute ppb values of the TVOC are most often not to be trusted.
What they are good at is detecting spikes, e.g. from cleaning liquids, desinfection etc. but I would not trust the absolute value at all.
The big sensor manufacturers recognized that and newer generations of the Sensirion sensors are now just displaying an "index" instead of absolute measurements.