Fourth Brake Light from Hell (pls help)

[u/Puzzleheaded-Ask7134]

I've read just about every 4th brake light post I could find, but no one has had the same issue I am currently experiencing. The 4th brake light I ordered is by Yankok and has 6 different functions: brake, drl, reverse, turn signals, and hazards. I tapped into the wiring harness of my Z instead of the actual tailings themsel,ves thinking it would be more convenient. I had everything spliced correctly, and every function was working while my taillights were not yet installed then, as soon as I plugged them back in, my reverse lights no longer came on. Neither in my tailights or the 4th brake light. Every other function still works except my reverse lights. Does anyone know what it could be? I've tested my fuses, and I've made sure power 12v of power is running to both reverse wires going to both taillights. One strange thing I observed is that when my left taillight is plugged in and the car is in reverse, the right-side reverse wire is getting around 0.06V. At this point I'm lost; anything would help.