Wrong voltage in logs

Hi dear community. I`ve got a hexa on X8 powered by 12S battery, fc is Cube orange.
I found out that the voltage is actually good, it drops only 5v during flight, and is displayed correctly both in the mission planner data tab and on osd picture, as well as measured by voltmeter…but! in data flash logs it is displayed large pressure drop, 20volts! i wonder what is the reason for such strange behavior…the voltage is being monitored through the 3rd pin using voltage divider 1/20

Share the log please.

https://drive.google.com/file/d/1Dv0i5bkZEp45cnuUQZnp64QCMKHGO-I4/view?usp=sharing
Thanks!

Interested in issue.

I found out that the ground of the voltage divider was not linked to the ground of the Cube power supply, cause its mounted on a different ubec. The problem with the voltage drop in logs is solved, I bridged 2 grounds together