I’d be surprised if recovery works. They would likely have taken off your phone number and recovery email and other backup methods. If they didn’t, they left a hole open you could use to get your iCloud account back. And worse for them, you could get Find My iPhone back and see where it is and activation lock it. Activation lock is bad news for thieves because it makes a costly iPhone become worthless.
So I guess keep trying account recovery. But chances are, in this situation, it’s gone. You may need to think about picking up the pieces and starting over with new accounts.
That’s not to blame you or anything, I think what happened is that criminals got smarter. They now watch people relentlessly in public spaces and you do one slip up, they remember your code, they have someone outside mug you for your phone and it’s all gone. In the months and years prior, thieves were stealing iPhones and finding it impossible to sell, impossible to get money off it, there used to be methods over USB to take iCloud locks off, and now those methods don’t work on the latest SoCs. So they adapted. So what can you do. Maybe next iOS version has something.
And for anyone wondering, security keys for iCloud can be taken off an account with the passcode, as well as numeric recovery keys. Apple takes the blame for centralizing the whole shebang, a device with passcode controls all the other security features. Oh, and the screen time PIN can be reset with phone passcode, so that’s not a solution either.