The brake pad "squealers" are telling you to have the brakes checked.
I wonder if it is because the Prius' regenerative braking system slows the car which means the brake pads are used less than a normal car.
Brakes on any car car squeal or squeak for a variety of reasons: 1. Very hard brake compound. (Metallic Compound Pads) 2. Worn out Pads with a wear indicator device. 3. Foreign material on the rotor or pad. 4. Anti-squeal material not used when Pads installed. If you changed the Pads yourself, did you use the anti-squeal paste? Either check the brakes yourself for items 1 thru 4, other take the car to a mechanic for a brake check.
There are several things that may make your brakes squeal. The most common causes are a lack of lubrication and worn brake pads. Less common (and not all agree that it is a cause) is dust and grime in the brake system. The best thing to do is to take your car to a mechanic and have your brakes checked and make the necessary repairs.
Some brake pads have a built in "squealer" to worn the driver that the brakes are in need of service soon. Have a trusted mechanic inspect the brakes soon. Waiting may cost you more money in repairs.
At least inspect when you hear squeal. Base further work on what you see.
If they squeal or make hard noises, or if your brakes are spongy or don't work then they need replacing. Or at least a simple servicing like repair or cleaning.
It is wishful thinking. It is more likely your brake pads are worn down and need replacing - an expensive garage job!
hypothisies
hypothisies
Your brake system needs repair immediately. The brakes are squealing because the pads are worn out, and you are hearing the warning device or the metal to metal contact of the pad and rotor. Stop driving the car and have the brakes repaired. The ABS light may or may not go out. If it does not, there is problem with the ABS. Your standard brakes will still work.
That could be the brake pad "squealers". They are designed to squeal when they are worn out. Time for a brake job.