[zazaulola]

ESP32 has 18 ADC input channels. But if you are using Wifi, you can only use 8 of the 18 for ADC conversion: GPIO pins 32-39.

Other 10 pins, on which ADC2 channels are possible, can only accept pulse data if you are using Wifi.

This is probably due to firmware limitations.

[mystified5016]

Espressif implies that the WiFi hardware uses ADC2 for something. It sounds like a hardware limitation, a firmware issue would have been patched a long time ago.