What does this flex cable do?

This cable connects the Main board to the Side board. The Main board connector melted off when my battery overheated and expanded so I can't connect it back. Not without learnibg micro soldering. Everything seems to be fine. Powers on, charges fine, SIM/WIFI is working, microphone still works. Google says SIM card socket holder connect flex, but my mobile connectivity is still on.

Edit: Zenfone 9