If that is the case, the sound is not coming from the “brake pad low” warning indicators. The “low warning indictor tabs” rub against the rotor especially when the brakes are applied.
That’s completely backwards. The tab starts vibrating against the rotor as the wheel spins once it gets close enough to just drag on the rotor. The high pitched squeal is that tab vibrating.
Once you apply the brake the tab is held firmly against the rotor. It might continue to make some noise but the clamping down on the brake rotor stops the kind of vibration that makes the noise.
As waterboy said, checking the lug nuts is not a bad idea. But you’re likely to find the squeal is the brake warning indicator tab.