Rear brake light/turn signal fault

I’ve been getting a sporadic fault from the right rear brake light & turn signal. It usually happens after a tropical rain. Tested the bulbs and they are still working—everything is fine the next morning.

Any suggestions?

Here is the scan from Carista:

Body/convenience system:
02743 - Right brake / turn signal lamp

Heater & air conditioning:
00797 - Sunlight Photo Sensor (G107)

Engine:
P1923 - Please Check DTC Memory of ECU Number 2

Engine (2):
P1573 - Left Eng. Mount Solenoid Valve, Open circuit

Radio:
00532 - Supply Voltage B+
00446 - Function Limitation due to Under-Voltage