brake is making nose

my brake is making the high pitch nose, even after i changed the rotor and pad.

it usually makes that high pitch nose when the wheel is slowing down right b4 come to competely stop.

i have no idea what make that nose, can someone pls help?

with the car up in the air and wheel off , spin the drum\rotor by hand , most likely a bent backing plate , spin each one by hand to figure out which ones are making noise

are u talking about that circle metal plate behind the rotor?
can i bend it back or i need to change them?

that's the plate, and you can bend them back... unless they are really bad