An USB isolator helps get rid of ground loops and lessens electromagnetic interference (EMI) involving the computer along with the linked gadget.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 that case It's not at all required because the 3V3 LDO IC1 is