Due to no reference device, we don't know the actual absolute humidity and its change.
I also can't confirm your results with your enviromental condition.
In our laboratory, temperature chamber and reference device are used to verify sensor performance and accuracy so that test results can be compared with them.
I understand that. I just don't have any absolutely accurate hygrometers available to me. To counteract that, I wanted to use a controlled environment (a sealed glass jar). I understand that you believe that the environment is not actually controlled. I undersand that you have doubts because there is no refference device but you also mentioned that the water may not be constant anyway. I am interested in knowing where those doubts come from. Where could this water content fluctuation be coming from? I know you cannot tell with certainty, but any thoughts and guesses you had are still valuable to me.
Because I don't repeat your experiment, any thoughts and guesses without actual reference data are uncertain and untrusted.
Some internal documents will be shared under NDA and even we are prone to verify your experiment.
So more support, please contact the local FAE to get.