An USB isolator aids reduce ground loops and lessens electromagnetic interference (EMI) in between the pc and the linked product. 1x GND 3V3 (P2 with 2 pins 2.54mm) connector can be employed to energy externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in that scenario it https://hydrabus44206.total-blog.com/little-known-facts-about-hydrabus-58393897