Intermittent vibration on 2018 RX 350 AWD between 40–60 mph

I have a 2018 Lexus RX 350 AWD with about 96,000 miles. Recently, I’ve noticed an intermittent vibration when accelerating, usually between 40 and 60 mph and around 2,000–2,200 RPM.

I mainly feel it through the accelerator pedal and the floor near my feet. It doesn’t really come through the steering wheel, and the whole car doesn’t shake. Sometimes I can also feel a slight vibration when I let off the gas.

Has anyone with a similar-year RX 350 experienced this? What ended up causing it?