You have one of the most complicated and intricate fast cars on the road, with some seriously expensive drive and recovery systems built in, not a car to be guessing from a second hand internet description what the fault is, nor attempting a fix unless you know what you are doing.

The only place that would be going for diagnosis if it were mine would be the Lexus workshops, from their diagnosis you can decide how to proceed.

Unusual car, one i could certainly live with.

Before getting involved in changing wheel bearings, assuming they have been checked by looking for movement at the wheel circumference, and there is no roughness when spinning the wheel, check the circumference of the tyre tread on the inside.

Run your hand flat around the tyre inner edge looking for or feeling for the treadblocks where can feel their edges sharp in one direction but smooth in the other direction, this is called feathering or scalloping and will make a buzzing or humming noise at speed - cheaper than replacing bearings!