I found the reason! It's because of the smart HDR. Disable this option and there will be no more signal problem
Hi all, I have my pc and ps5 connected to my new G3223Q monitor. When I switch the source to the ps5, no problem. But when I switch back to the PC source, no signal is detected. I have to unplug and replug my cable to get the signal from the PC. It's very annoying. Please don’t tell me to disconnect/change cable or hard reset monitor, I have already tried and nothing changed. 
G3223Q, HDMI signal lost when I switch source