with the posted setup and posted code, my charger gives 5V.
if i delete the loop part of the code (to force the charger to still at 12V) the charger give me 5V. but if i disconnect the white QC cable and i re insert in the board, the voltage go to 12V. so the problem is not the setup. i think the problem is code-related, like the nano dont do the handshake with my QC controller (and i dont know why he does if i disconnect and reconnect the white wire)