Scraping/rattling sound when engine is running + poor fuel economy

When the engine in my 2015 prius (105k miles) is running, there is a scraping/rattling/grinding noise from under the car. At first I thought it sounded like the heat shield rattling which I've had fixed in the past, but it's not rattling in quite the same pattern as the heat shield was. I'm also getting significantly worse gas milage.

It stops when the engine isn't running and the car is using the hybrid battery, moving or idling. It occurs when the engine is running whether I'm moving or idling/parked. It gets louder when I'm accelerating and sometimes quiets down briefly when I'm coasting. The sound is not rhythmic with tire rotation or sound like its related to braking.

Shortly after this first started, my brake lights came on and I took it to a shop to figure out the issue. They fixed a rear wheel bearing which made my brakes feel better but didn't fix the noise or gas milage.

Anyone ever have a similar issue or have advice or ideas?