Rain accumulation disagreement: picker vs meteogram

[Baldo1191]

I read that the rain and thunder layer shows the sum of the precipitation of the last three hours. If I compare the information from the map (red circle) with the sum of precipitation shown in the meteogram (red rectangle) I have no correspondence. The picker indicates 7.4 mm of rain, in contrast the meteogram shows 9.8 mm of rain (sum of precipitation of 9pm, 10pm and 11pm ). Why do we have this disagreement?

Many thanks!

[Yves70]

@baldo1191
I gave you an asnwer in another post