I wonder if your brake pads are very hard (like ceramic), if they are you have the same brake squeal I get once in a while.
Mine squeals on the first light application, sometimes twice, then no more until maybe the next time I use it, sometimes no squeal. Being retired, the car isn’t used every day.
When I bought the (used) Toyota Matrix early '09, the dealership replaced the rotors, pads and tires.
I took the car to my independent tech and he inspected the brales and said there is no damage to the rotors, but because they put ceramic pads on they sometimes squeal.
The brakes will stop the car on a dime and give you 9 cents change so I know they work well.
Wet weather causes overnight rust build up on all rotors but normally the grinding is more like a growling not a sharp, high pitched squeal.
Summer time brings quiet braking.