I had the whole creaking thing and occasional thud on my 2018 RX450h, purchased used last September. The Lexus dealer first cleaned and changed the pads- no lasting effect - and on my second visit I took the car out with one of their technicians in the car listening - he immediately diagnosed the brake actuator - which I believe distributes the pressure evenly to each wheel- and is a known fault within Lexus. That part was replaced by the dealer, and problem solved - 7,500 miles later and no hint of the creaking from before.
