Mike
I have an RX450h+ and an NX450h+ and both are 2024 models. The noise in the NX is far more noticeable than in the RX. It is first audible around 12 to 13 mph up to 22 mph and disappears at 23 mph and above. It's barely audible in the RX model. I believe that it is the eCVT transmission causing this noise, as it is present in both EV and HV modes. Both of my cars have very low miles, since they are 2 months (RX) old and 2 weeks old (NX) but, that is my take on it. I will bring it up at my 5,000 mile service appointment to see if this is the issue.