Breaks issue

I had new front breaks last year but something now squeaks during medium breaking. It got no advisories a few months ago but the service today said there's nothing wrong. I thought it was something that needs adjusting with the new ones but the back ones have gone down from 5mm to 3 in 2000 miles.

AI said this is probably a stuck back calliper or stuck hand break cable.

Does that sound accurate? Thanks.