Wifi syncing stopped working - Big Sur

Recently, I found out that the iPhone icon is not on my Mac Finder anymore... iPhone's icon appears when it's plugged in, but when I remove the cable the icon also disappears!!!

Guys, I have followed the steps of "how to sync iPhone and Mac wirelessly". Don't repeat those steps I have followed them and have done it many times.

Eventually, I talked with four different people from apple support and they couldn't help me!!!

I also found out that if I could kill "AppleMobileDeviceHelper" in the "Activity Monitor" the problem could probably be solved. I couldn't find it on Activity Monitor.

Does anybody have the same problem? It's boring to use a cable for transferring files every time!!!

Would be grateful for any help.......