It's your brakes. Brakes appear to be fine to a lot of people. About half the "meat" on brakes is not brake material, but for cooling. That's why when you look at the squealers they make it look like there's so much brake left when there really isn't. People tend to run their brakes right down, even taking the squealers off cuz they think it's a marketing scam, it's not. If it actually is the brakes then change them, don't try braking with that cooling material, you won't stop as well.
Does it squeak when idling? When revving the engine while not in gear? When going backwards? How loud? Does it come back when decelerating under 45? Ask someone to drive past you and listen if it sounds louder from outside. If it goes away past 45, it could be something with the transmission. Check fluid color/level. When was last transmission service?
Cruising through the workshop manual, I was more than surprised to see that the pad specs are 11mm new (0.433 inches), but more importantly the minimum worn thickness spec is only 1.6mm or 0.063 inches. As much as I love to avoid replacing pieces when they don't need it, letting the pad material get thinner than the box new ones arrive in is NOT A Good Idea, in my limited experience. Especially the factory pads, which are notorious for not having enough temperature tolerance even when new. Pads are too cheap and too easy to change, vs risking stopping, comfort and noise issues. By the time pads get to 6mm (about a quarter of an inch) I'm shopping, and by 4mm (about 3/16") I'm replacing them.
The pads include two-part pad anti-vibration shims that sit between the caliper and each pad's backing plate. Two pieces behind each pad. There are two wire pad return springs that push the pads back away from the rotor so they don't drag. The upper and lower springs may be slightly different, so take careful note (read: pictures) of their installed position before removing them. After that there are two pad retainers that offer a sliding surface for the pads while holding them in the caliper. The upper and lower retainers are different (more disassembly pictures), with the upper folded tighter to receive the braking force and the lower more of a spring to maintain slight pressure on the pads. The retainers and the edges of the pad backing plates get lubricated so they can slide and retract correctly. All of these parts are critical to avoiding pad vibration and the "brake squeal" that results. The retainers must be maintained clean and lubricated, not packed with brake dust. The retainers must not be mixed up top and bottom. Needless to say, if all these parts aren't installed and installed correctly, noises and excessive brake pad wear are a risk.
DIY pad swappers may rush through a swap, not taking care to put all the pieces back in correctly. They may not get the pistons fully retracted, and so may find not enough room for the anti-vibration shims. Might get the retainers mixed up, not get the wire return springs right, and have vibration/noise/excessive wear symptoms.
You get the wear indicator ding when you arrive at 1.6mm. Why replace it sooner, if it works? I always wore my pads down to the indicator, and once I hear it, I replace them. This way they last 70k miles and I do not feel any difference before and after.