[villagetinker]

Try changing the light bulbs, I am assuming these are LED type, and I have seen strange operation when they are starting to fail. I would change all four bulbs and see if the problem is eliminated. Next would be changing the dimmer, once again I have seen strange operation with these. Double check that all wires are tight on the dimmer. The last item may require an electrician to check the wiring connection in the first light in the string of lights as i have seen intermittent operation that clears up when the connection heats up.
Does this happen all the time, at all times of the day? Are there any other electronic controls on these lights (Alexa, Apple,Ring, etc.)? Are all the lights the same, all LED or all incandescent?