I was in a rush, so I didn’t fully-articulate my point, although that was also before you posted your actual usage timetables. You have a base load somewhere in the neighborhood of 2 kW. In those hours showing 10k - 12kW, that differential 8k - 10kW jump is probably not spread evenly over the full 60 minutes of the hour. Just applying the law of averages, which is still likely conservative, you have more like a 20kW jump from your base load, over a span of 30 minutes.
When talking those sort of differentials, one would expect to see dims and surges over a main of any length, independent of the quality of the panel at the end of those mains. A 20 kW differential is a 90 amp change in your load, or your base load jumping from 10 amps to 100 amps. That is substantial.
Now, you’ve posted your timetables, and they don’t completely agree with my assumptions. Those days showing 10kW and 12kW single hours seem to have much higher base load, thru most of the day, no? I’m viewing on a phone, so maybe did not get as complete a view of them as I should.