Chewing The Fat..... "Volt-Drop"...

[UNG]

Out of interest, was there a lot of PV in the immediate area?
I had similar, and my suspicion was that in this upper class residential area a lot of early PV adopters without battery storage and lack of daytime loads was pushing the supply voltage up. I couldn’t prove it though.

You have guessed correctly
Seems to be the norm these days and it is becoming more difficult to avoid the inverter dropping out due to the high grid voltages although it could be good for selling battery storage