"Gave away the Bronco game" is a little strong. I'm no FFF but he did more than his fair share to put the Bears in a position to beat the Broncos. The defense not being able to get off the field in the 2nd half was not his fault.
The fumble six I place the blame more on the non existent blocking of the free rusher in Fields face. You could make the argument that he should have ate the sack but it's hard for most any QB to process that with a defender running free right in your grill. I'm cool with giving him a pass on that one.
The INT is a different story. Looked like Fields was the one responsible for the miscommunication as Kmet appeared to have his man beat. I can't absolve Fields on that one.
All in all, Fields led scoring drives to help the Bears take a 28-7 lead deep into the 2nd half. Defense and coaching were more to blame for the collapse IMO.