iPhone 13 Bluetooth connection

The first thing I would check is whether or not your phone can connect to other bluetooth devices. I would restart your phone and just test the bluetooth with some other devices to make sure it works in general, then try connecting to the panel.

If no luck, reboot the panel (Settings > Advanced Settings > Reboot Panel)

If no change after the reboot, try again after updating the firmware of your panel to the newest available per instructions here.