The last 10 days I have noticed flickering dashboard lights at the dash information screen, radio screen and overhead light cluster. The external lights front and back look OK. This happens occasionally and only after long time (at least 1/2 hour) of engine operation. If I switch off the engine they go normally, and after switching on they are normal again.
At my visit to the dealer –guess what- the lights were normal. Dealer checked the battery and the charging process, both ok. The diagnostic equipment hadn’t stored any fault codes. Dealer said when I notice that again to bring the car back to have it checked. Probably is due to undercharging or overarching with the latter to be dangerous for the vehicle electrical systems.
Any idea on that?

Car is 4 1/2 year old with 145.000KM