Found impact bit under car
Did I just get my catalytic converter stolen? No excess sound or check engine light yet, but the bit was absolutely not mine.
Do people use impact bits to steal catalytic converters? I have no idea what it looks like so I can't tell with my eyes.
I’m no expert but I think they use a sawing tool. I would also expect the vehicle to be noticeably louder since, as I understand it, the CC is between the muffler and the engine. The vehicle basically ends up with ‘straight pipes’ which should be very loud!
Is your car any louder? if your catalytic converter’s gone then you’re not utilizing the muffler any longer, Catalytic converters are between the muffler and the engine
You would immediately know if it was stolen when you started your car.

They do not use impact tools to remove them, they use cordless sawzalls.

The simplest explanation: somebody was working on something, put a socket on their bumper/roof, and forgot about it, and it fell off when driving along. Congrats on your new impact socket.
Start the car.

Is it loud?
Not really.
Lol this comment thread went from helpful to paranoid gang stalking real quick.
I've been getting downvoted since I started the thread. You'd think people would be sympathetic to my catalytic converter getting stolen, but I guessed wrong.
Your converter wasn't stolen. Without it your car is straight piped, which would make it extremely loud.