On the flip side, mains-voltage LEDs generally have built-in power supplies which should lead to them actually showing less dimming during brief voltage dips.
Some mains-voltage LEDs in fact flicker at twice the mains frequency! This is visible when you turn your vision, or when something moving, like rotating fan blades, is illuminated.
The Phillips flood lights in the track lighting fixture in my kitchen are like this.
They contain some sort of very light-weight power supply to rectify the line voltage and adapt it to the LED, but there is no LC capacity in it to even smooth out the 120 Hz ripple.
There is no room in those bulbs for the electrolytics/inductors that would be required.
