Simultaneous Dimming

Hello,

First time long time. Recently moved into a house and I noticed all the lights in the home will dim at once—hold for about 10-15 seconds and come back up to full brightness. This does not coincide with an increase load ie AC kicking on, large freezer etc. I had the utility company come out and check the utility side for a loose neutral, taps, transformer connections. They reported back that all was good on their side. They did not notice any fluctuations in AMPs.

Could this mean no ground or damaged ground running to my breaker box on the residential side?

Inspector never caught this bc you’d have to be here at the right time to catch them all dim down.

Any starting point for trouble shooting would help.