Professors using Turnitin AI scores like gospel and its stressing me out

Im a junior in college and lately my English prof has been all about these Turnitin AI detection scores. I turned in a paper and it said 45% AI even though I wrote every word after brainstorming in my notebook. Had to email my whole draft history and timestamps just to prove it was mine. Now every assignment feels like a battle. Anyone else dealing with this? How do you fight back without seeming sketchy? Starting to feel like we cant trust the tool or the profs who rely on it so much.