Summing visits in different methods (Bug?)

Hello, I have an issue with the sums Matomo returns in different widgets respectively different analysis methods. For example “Visits Overview” vs “Channel Types”: Comparing every day of a 14 days period the amount of visits in “Visits Overview” is equal to total visits in “Channel Type”.

Comparing the first week the amounts are also equal (sorry, no two images possible, but the amounts are equal).

Comparing the second week the amounts deviate extremely (see image below)

Sometimes the sum in “Visits Overview” is wrong, sometimes the sum in “Channel types”.
This issue occurs with no regularity but I found no way to avoid it. And I’ve got also no chance to update the values, if this issue occurs (except from deleting all reports and running into the same issue anywhere else on generating the reports again).

I use Matomo 4.2.1 on premise an analyzing logfiles.

Thank you for your advice and help.