Had this happen right after an update as well. In docked mode the controller is fighting a lot of 2.4 gigahertz junk from the TV area. The quickest fix for me was to flip the controller to wired. Go to System Settings then Controllers and Sensors and enable Pro Controller Wired Communication. Connect a USB C cable from the dock to the controller and it will stay solid.
If you want to stay wireless try pulling the dock a few inches away from the TV frame and any hard drives or hubs. Then update controllers from the same menu and re pair after holding the tiny sync button for about fifteen seconds to fully reset the pad.
