An USB isolator can help get rid of floor loops and reduces electromagnetic interference (EMI) amongst the pc and also the related device. 1x GND 3V3 (P2 with two pins 2.54mm) connector may be used to power externally the WCH CH569 MCU (it is suggested to eliminate the P4/SHUNT in https://geraldp273zqh8.dailyblogzz.com/profile