Reported RPM clarification

Hi all,
I’m working to analyze the log data coming in from our Zubax Komar controller.

Just wanted to clarify - the reported RPM in the Ardupilot log, under ESC.RPM is the actual, measured RPM of the motor, or is it a calculated value?
More specifically - if I’m working in Voltage mode, sending the same command to the ESC and then increasing the loading on the motor or decreasing the DC bus voltage - will I see the logged RPM change accordingly?

We are working with Komar ESC with Telega0.3.

Thanks

It is the actual RPM.