The car has HPS Ferro-Carbon brakes with a warped Brembo rotor at the place where the squeal is most likely coming from.

The squeal sounds similar to a fork or spoon scratching along the surface of a glass or porscelain/Chinaware. The squeal is very noticeable when I slowdown from 20mph to a stop.

Before this noise happened, I disconnected the front left tire, to rotate a crankshaft bolt counter-clockwise, to see if I could rotate the distributor rotor.

I Googled the problem, and it's supposed to be a warning that brakes are fading. I've had the brakes for less than 25,000 miles. Most of that 25,000 miles was on the highway. The rotor became warped (or noticeable warped) after 3,000 miles of usage.

I was thinking of inspecting the brakes myself, but I'd need to get C Clamp, Brake fluids, and possibly a breaker.
I've never done brake work before, but I’m leaning toward inspecting the brakes myself, so I know how to replace them in the near future.

As a result of Googling, I didn’t find an answer for the squeal in regards to very low speeds. May someone please tell me the lifespan of ferro-carbon brakes?

Edit:
I disassembled the brake bracket. It turned out the inner pad had uneven wear due to a stuck (fused) brake caliper/slider pin.

I place the blame on an incompetent (or scamming) mechanic who's shop closed down, for whatever unknown reason. Second time (link) a brake/rotor installation job by him resulted in brake slider pins behaving they way they shouldn't. Also he let my brake caliper hang on to the brake line while he was installing them. I didn't know this was bad thing until I read youtube comments.

His shop's facebook page, comes up as "currently unavailable". I wish I could a cache for it, but the Google results to the top 3 site, doesn't have an archive. I wish I could warn others about this guy. I don't think the mods would approve of personally identifiable information.

I'll have to order new brackets, rubber housing, and brake sliders.