Ill tack on - Partially compromised neutral service lateral.There is a good chance....
Possible sources of excessive voltage drop are:
POCO transformer with high impedance
Loose connections at the POCO transformer.
Long or undersized service drop conductors.
Loose connections at the customer side.
I second this. You can probably recall a nearby speaker picking up spike and making a popping sound when you turn something on/off nearby. Such interference can travel into different circuits and can disrupt the peaceful state between LED ballast and dimmer. The severity of reaction and resistance to such impulse is greatly dependent on each dimmer and ballast. For example, first generation CREE LED bulb was very susceptible to spike that sometimes a spike from turning off the bathroom/laundry room fan would cause the lamp to turn off and back on. This wasn't due to a voltage drop. It was the bulb's ballast acting up due to poor design.The first thing you need to determine is if you have a true voltage drop issue.
In the old days, if you saw an incandescent light change brightness then you knew the voltage changed.
With dimmable LEDs, very small voltage fluctuations can trigger the dimming circuitry and cause much larger brightness fluctuations than the actual voltage change should cause.
Plug an incandescent lamp into the circuit and see how much flicker you get.
I’m lucky in that aspect as well. My closest residential neighbor is fed from a different direction and mine taps from POCO primary upgraded for summertime irrigation loads. There is no VD problem at my house.I think I've been spoiled by our almost constant 122vac PoCo service.
They've also cut down so many branches that I'm no longer shopping for a gen but it does uglify the neighborhood.