I have a 2015 Prius and there is a blue flashing light on the driver's side under the dashboard.

It is your anti theft device,

No, it's not the red flashing icon on the dashboard. It is a blue flashing light from under the dashboard somewhere on the driver's side.

New car,should have manual there in it took look at,but that dim blue light want be in the manual,ask your dealer he will say the same : )

I've been driving the car for a month and this is the first time I've seen the blue flashing light. It's a pretty strong flash of light. Something doesn't seem right.

Some dealers, put shut down and gps on cars that are finaced to keep up with them and can shut them down when needed,lf you bought it out right,have them remove it,or at least tell you the same as i did,

Hint.