High voltage drop on Nano outputs caused by sketch

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Try this

// RPM_footswitch_x8_v2_F
// mchambers 6/19/2025
// for Nano
// a sequential counter that drives RPM preset control inputs, with bypass function (preset1)
// Sketch works but voltage drop on outputs is too high and increases from D9 to D2
// D9=0.8V, D8=1.13V, D7=1.45V, D6=1.81V, D5=2.27V, D4=2.66V, D3=3.04V, D2=3.44V
// Can the problem be saving the last bypass/select state? I don't think they need to be saved.
// Removing the last state save makes it almost impossible to get one preset increment; switch bounce
// Increasing the delay to 200 fixed the one increment issue
// The Vdrop is better: 1V to 3V range; but still terrible. Should be 0.25V or less
// Removing the "if xxxState == LOW" shifts the Vdrop: 0.8V to 3.5V = back to square one
// As the Select switch is pressed, the selected output has less voltage drop for an instant; WTF?

// Constants won't change:
const int bypass = A0;
const int select = A1;
const int preset1 = 9;
const int preset2 = 8;
const int preset3 = 7;
const int preset4 = 6;
const int preset5 = 5;
const int preset6 = 4;
const int preset7 = 3;
const int preset8 = 2;
byte presetPin[] = {2, 3, 4, 5, 6, 7, 8, 9};

// Variables will change:
int bypassPushCounter = 0;   // counter for the number of Bypass button presses
int bypassState = HIGH;      // current state of the Bypass button
int lastBypassState = HIGH;  // previous state of the Bypass button
int selectPushCounter = 1;   // counter for the number of Select button presses
int selectState = HIGH;      // current state of the Select button
int lastSelectState = HIGH;  // previous state of the Select button
int lastPreset = preset1;

void setup() {
  pinMode(bypass, INPUT_PULLUP);
  pinMode(select, INPUT_PULLUP);
  pinMode(preset1, OUTPUT);
  pinMode(preset2, OUTPUT);
  pinMode(preset3, OUTPUT);
  pinMode(preset4, OUTPUT);
  pinMode(preset5, OUTPUT);
  pinMode(preset6, OUTPUT);
  pinMode(preset7, OUTPUT);
  pinMode(preset8, OUTPUT);
}
void presetOffAll() {
  for (int i = 0 ; i < sizeof(presetPin); i++) {
    digitalWrite(presetPin[i], HIGH);
  }
}
void loop() {

  // read the Bypass switch:
  bypassState = digitalRead(bypass);
  if (bypassState != lastBypassState) {
    if (bypassState == LOW) {
      bypassPushCounter++;
    }
    // save the current Bypass state as the last state, for the next time through the loop
    lastBypassState = bypassState;

    // Delay a little bit to avoid bouncing
    delay(200);
  
  if (bypassPushCounter == 1) { // Bypass mode
    digitalWrite(lastPreset, HIGH);
    digitalWrite(preset1, LOW);
  }
  if (bypassPushCounter == 2) { // non Bypass mode
    digitalWrite(preset1, HIGH);
    digitalWrite(lastPreset, LOW);
  }
  if (bypassPushCounter > 2) {
    bypassPushCounter = 1;
    digitalWrite(lastPreset, HIGH);
    digitalWrite(preset1, LOW);
  }
 }

  // read the Select switch:
  selectState = digitalRead(select);
  if (selectState != lastSelectState) {
    if (selectState == LOW) {
      selectPushCounter++;
    }
    // save the current Select state as the last state, for the next time through the loop
    lastSelectState = selectState;

    // Delay a little bit to avoid bouncing
    delay(200);
  
  if (selectPushCounter == 1) {
    presetOffAll();
    digitalWrite(preset1, LOW);
    lastPreset = preset1;
  }
  if (selectPushCounter == 2) {
    presetOffAll();
    digitalWrite(preset2, LOW);
    lastPreset = preset2;
  }
  if (selectPushCounter == 3) {
    presetOffAll();
    digitalWrite(preset3, LOW);
    lastPreset = preset3;
  }
  if (selectPushCounter == 4) {
    presetOffAll();
    digitalWrite(preset4, LOW);
    lastPreset = preset4;
  }
  if (selectPushCounter == 5) {
    presetOffAll();
    digitalWrite(preset5, LOW);
    lastPreset = preset5;
  }
  if (selectPushCounter == 6) {
    presetOffAll();
    digitalWrite(preset6, LOW);
    lastPreset = preset6;
  }
  if (selectPushCounter == 7) {
    presetOffAll();
    digitalWrite(preset7, LOW);
    lastPreset = preset7;
  }
  if (selectPushCounter == 8) {
    presetOffAll();
    digitalWrite(preset8, LOW);
    lastPreset = preset8;
  }
  if (selectPushCounter > 8) {
    presetOffAll();
    selectPushCounter = 1;
    digitalWrite(preset1, LOW);
    lastPreset = preset1;
  }
 }
}

Needs auto-formatting, but I'm on my phone right now.