This actually just happened to my daughter who lives in another town. She bought a good used car, within a few days she started to have the same noise and symptoms. I had my Son in law get off his butt and go jack it up. Lugnuts loose and it had already ruined the wheel. They called the used car dealer about it. Apparently they had just swapped wheels and tires from another rig onto this one. The incompetent tech forgot to tighten one of them.
And even if you have not had the wheels worked on recently, someone could have loosened them, or if they were not properly tightened even a year ago they can still loosen over time. And they will come loose faster on the left side than on the right side.
Errrr. You just caught my attention. I’m going through a rather nasty divorce at the moment and the mechanic who did the caliper work is no longer employed at the dealership.