Vibration under load at 1500 rpm

[slogh]

I have a 2015 Impreza (CVT). Just passed 100K miles. I have a vibration that sounds to come from the front passenger footwell area while driving and engine speed is at 1500 rpm. It happens at different speeds but always at 1500 rpm (engine speed) and the accel pedal has to be pressed (if coasting and rpm is at 1500 no vibration is coming through). There are no DTCs or Check Engine light. The spark plugs were replaced at 63K and fuel filter at 92k. I recently did a tire rotation and the vibration didn't change at all. The vibration isn't affected by engine temp either (happens if cold or hot). I replaced both front and rear diff oil at 60K and drained and filled (5 Litters) of CVT fluid at 66K. Vibration doesn't happen when in Park or Natural (car has to be moving and light pedal). I also checked the CV joint (front and back). I am no expert but there wasn't any clear cuts in any of the CV boots. I haven't noticed any drop in power (even when the vibration is happening). Once I either release pedal or increase the pedal (engine rpm increases) the vibration goes away.