Issues with Millis function and sensors

[J-M-L]

Random behaviors come sometimes from power issues. How did you wire everything?

@roommate2021

for (int i = 2; i < 8; i++)
    avgval += buffer_arr[i];
  float volt = (float)avgval * 6.00 / 1024 / 9;  //5.0 volts

You are summing 6 values (index 2 to 7), your formula seems weird to calculate voltage