MQ2 sensor. pls help with config

physically, i wired the MQ2 as such:
MQ2===================NodeMCU.
A0-------------------------------------A0
D0-------------------------------------not used
GND-----------------------------------GND
VCC------------------------------------5V
on the ESPHome config, i have it as such:

sensor:
  - platform: adc
    pin: A0
    name: "MQ2 sensor"
    update_interval: 10s
    filters:
      - multiply: 3.3    

on the graph, i see it getting lower n lower n lower. what’s going on here?

The concentration of organic solvents in the air is changing, or the sensor may be drifting with temperature.

Does it react if you blow some fumes over it?

oh, looks like i have to wait at least 24hours according to this site, right?..https://lastminuteengineers.com/mq2-gas-senser-arduino-tutorial/
I also see it is powered by 5V. but is 3.3v from the nodemcu good enough?

currently it is sitting by my window. i dont have any of these fumes to test it out atm: i-butane, propane, methane ,alcohol, Hydrogen, smoke. i will try to get some isopropyl alcohol by tomorrow.

Oh yeah. I forgot about the preheat time. Also, yes you should be powering the heater from 5V.