Gravity I2C Oxygen Sensor (SKU SEN0322). Drift??

I'm developing a network of low-power consumption air sensors.  I'm using this sensor with a 3.7V battery where the power supply is switched on-off, in order to lower the consumption.  When it is switched on, it waits 20 seconds in order to reach the correct value as indicated in the datasheet of the sensor (not the module) and then, several measures are taken before it is switched off again.  These actions are repeated every 5 minutes and I can see an important drift that in a couple of hours can exceed the free air concentration value of 20.9%.  Here is a plot of that drift.

Anyone can help me?

Thank you!!!