Who’s at fault here?

If you run into someone's back you're at fault, just how it is tbh. You should allow enough space for a situation just like that one.

The Prius forced contact, classic case of insurance fraud. There was no reason whatsoever to slam the brakes there.

The one who failed to leave enough space to safely stop on time

Both! The Prius for the insurance scam driving; The second car for the music 😒

@AMAZlNGNATURE Definitely the driver using a phone to record while driving

Clearly the Prius. The left hand side is the fast lane. You don’t get to just break like that. Shit can cause an accident and in this case it did. Thankfully a minor one

Proper following distance above 35 mph is 6-8 seconds. The car recording was too close and gave themselves no space cushion for stopping. They are at fault. (I'm a DOT-certified trainer/examiner. This is literally my job. lol)

car behind is typically at fault. Front car can stop if they want to.