Weak cable voltage - what is the reason?
In one cable, which goes from the distribution panel to the two-gang switch (kitchen + hall), the voltage is low, the indicator is lit weakly. When the switch is turned on, there is no plus on the lamp in the hallway, but everything is fine in the kitchen.
Check for voltage between the phase that goes to the hallway lamp and zero. Voltage is checked with a voltmeter or multimeter in voltage measurement mode. If there is no voltage, then somewhere there is a break: either there is no normal contact at the point where the wire is connected, or somewhere in the wall the cable is damaged.