Designers were likely relying on the curve of the piece to provide the strength to help keep it place. This is the OP's second Prius, it might have the updated part. Looks like those side clips were just pulled out when the bar flipped to concave. Perhaps the heat softened the plastic they anchored too, or weaken the tension of the clips. Being left off to begin with is another possibility.
the “dent” is a warp from it being hot and bent. But yes you guys are correct the previous owner had the emblem painted (or swapped). Can’t see why you would take the bumper apart to do that.
Thanks for all the insight guys. I haven’t had time to take it in. But I will soon. Yes it was VERY hot out through the desert. I believe it just got weak from heat, soft, and with the hours of constant 80mph wind, it buckled. Obviously I do not know with certainty if the previous owner did anything but the car is in perfect condition with 7k miles. Emblem shouldn’t have anything to do with it. Will report back. And and my previous Prius Prime, well it had a dead battery when I test drove it. I did find it odd but they got a battery pack and I knew it was warrantied but ya ended up wasting a ton of my time. Got all my money back but still. 3 months later.