Insurance paid way less than my bill - is this normal or did they mess up?

So I had an outpatient procedure done last month. My EOB came in and the insurance company says they paid their "allowed amount" of $420 on a $1,800 bill. I've met my deductible already for the year so i figured they'd cover most of it.

Now the provider is billing me the remaining $1,380 and saying i owe it all. I called insurance and they just kept saying the provider "exceeded the allowed amount." My plan is a PPO and this was an in-network doctor so i'm really confused how this happened.

Has anyone dealt with this? Do i have any options or am i just stuck paying $1,380?