2nd Canon lens to have dual nano USM to drive the focusing group.
From TDP:
Focusing
Unless in manual focus mode, a lens's autofocus performance is an extremely important factor in realizing the image quality capability of a lens. To that point, the Canon RF 100-500mm F4.5-7.1 L IS USM Lens, like the Canon RF 70-200mm F2.8 L IS USM Lens, gets an advanced, high-performing AF system driven by Dual Nano USM (Ultrasonic) focus motors.
While Canon has been designing Nano USM AF systems into the latest L-series RF lenses, this dual-motor design is being featured for only the second time in the RF 100-500. What Canon said about the RF 70-200 Dual Nano AF system again applies: "The lens also incorporates a floating focus control ... that drives the two lens groups individually while using the two aforementioned Nano USM motors. The floating focus lens element shortens focusing distance and helps reduce breathing, providing users with fast, consistent and reliable performance."
Nano USM acts like an ultra-fast version of STM AF, combining the benefits of a high-speed Ring USM actuator with an STM system stepping motor's quiet and smooth, direct, lead screw-type drive system. Like Ring USM driven AF systems, Nano USM focuses nearly instantly. Like STM AF systems, Nano USM focuses almost silently and very smoothly. Cameras featuring Dual Pixel CMOS AF and Movie Servo AF make video recording very easy, and Nano USM lenses are very well-suited for this task. The smooth focusing makes focus distance transitions easy on the viewer's eyes, and the sound of the lens focusing should not be picked up by the camera's mic.