Some LED lights are especially sensitive to mains voltage variations; this is usually the case with triac-dimmable type LED lamps. To create the dimmable control, these lamps directly modulate the LED current to be proportional to the absolute incoming mains voltage, so that a triac dimmer will cause the lamp to switch off at the right moment. However, if there is any noise on the input supply, they will flicker. I have an EV, and when I charge my car which pulls 7200W from a 240V supply, it causes the dining room lamp, a dimmable LED lamp from Costco, to flicker quite visibly. This is despite the car charging circuit being tapped right off just after my electrical meter on a dedicated circuit, the variation in supply voltage is clearly too much for the lamp.
The solution is simple, change the LED lamps for a type that is definitely non-dimmable, and which uses a regulated current circuit to drive the LEDs (anything that's not absolute bargain basement will.) Of course, if you want dimming, you'll need another option, like smart lightbulbs.