I tested everything again and i couldn't see any problem with connections or missing ground to the GND pins.
On the breadboard voltage it's stable after a while and oscilating around 360-380mV. But the same MQ2 sensor on the PCB oscilating around 400, 800, 1100 mV and it's not stable at all
I dont really get it. I've tried to use it with and without connecting to the USB (i thought that it's some GND missing and it could be stable after connecting USB cos the socket is a next GND, but no, still the same)
Maybe the ESP32 wroom 32 needs additional connection to GND apart from the GND and VIN on the board? But the documentation says that: VIN to 5V and GND nothing more. I double checked the 5V regulator and it's regulated the 12V to stable 5V. I'm using thick wire to provide 5V and GND, maybe it's an issue? Should i use thinner one? But the other hand all voltage at the MQ2 or temperature sensor shows correct 5V. Even the ESP from the VIN shows correct voltage. Only output from MQ2 shows floating voltage and i dont know why because on the breadboard it's perfectly fine. :V its frustrating.
I'm bet i missing something but i dont know what.