Resolved! [Cube/HAL ADC STM32F405] One of the ADC channels seems internally pulled-up.
I am using triple simultaneuos conversion ADC (2 conversions for each) with DMA (circular):static void MX_ADC1_Init(void) { ADC_MultiModeTypeDef multimode = {0}; ADC_ChannelConfTypeDef sConfig = {0}; /** Configure the global features of the A...