Yes, you're seeing the PWM operation of the DRLs to reduce their apparent intensity to provide the front position ("parking") light function. The same thing is done with headlamps to provide a DRL function, and stop ("brake") lights to provide a rear position ("tail") light function. It's called the "bead effect" and I agree, it's distracting. What's even worse is non-legitimate aftermarket "LED bulbs" installed in place of appropriate halogen bulbs in cars that use PWM to provide the DRL function via the headlamps; those not only flicker, but they appear to dance as viewed in a moving mirror (car or bike rear-view or side-view, for example).
People are stupid to put LED 'bulbs' in high beams. Obviously undesirable effects are the outcome, whether extreme flicker or nighttime collisions.i see it too, people put led bulbs in high beams, however drl high beams are driven at half the voltage, some led drivers can not deal with voltage so low so leds appear to flicker\strobe. it is annoying, to the point you get tired when someone with such lights is following you, you have to switch lanes away from them, or maybe it is the intended purpose.
What do you mean more specifically by "appear to dance?" To my eyes, all flickering lights (from DRL or tail lights) appear to dance while my eyes are steady on something, and create a phantom array during saccades.
The presence/degree of a "dancing" or wiggling appearance of the lamp is a function of the PWM frequency. If it's too low, this is the result.