why OUTPUT power in one situation is lower than in other by the same loop

Projects Programming
1

The problem is with level1, when it is activated, then on OUTPUT (leds on board) shins very weak both leds WHY???
But on level2 and lamp everything is OK.

const int level1 = 9;
const int level2 = 10;
const int level3 = 11;

const int motor1 = 3;
const int motor2 = 4;
const int lamp = 5;
int count = 0;
int stateON = 0;
int stateOFF = 0;

void setup() {
  pinMode(level1, INPUT);
  pinMode(level2, INPUT);
  pinMode(level3, INPUT);
  pinMode(motor1, OUTPUT);
  pinMode(motor2, OUTPUT);
  pinMode(lamp, OUTPUT);
}

void loop(){
  int L1 = digitalRead(level1);
  int L2 = digitalRead(level2);
  int L3 = digitalRead(level3);
  
  if (L1 != stateON){
    if (L1 == HIGH){
      count++;
    }
    else {
    }}
   else {
   }
    stateON = L1;
   if (L1 == HIGH){ 
    if (count % 2 == 0){
    digitalWrite(motor1, HIGH);
  }
  else{
    digitalWrite(motor2, HIGH);
  }}
  else{
  }
  if (L2 == HIGH){
    digitalWrite(motor1, HIGH);
    digitalWrite(motor2, HIGH);
  }
  else{
    digitalWrite(motor1, LOW);
    digitalWrite(motor2, LOW);
  }
  
   if (L3 == HIGH){
    digitalWrite(lamp, HIGH);
  }
  else{
    digitalWrite(lamp, LOW);
  }
}
2

Your code it very hard to read. Get rid of the empty else blocks and statements.

The problem is with level1, when it is activated, then on OUTPUT (leds on board) shins very weak both leds WHY???
But on level2 and lamp everything is OK.

level1 is an INPUT pin. What "shins" very weakly? The only only OUTPUTS affected when level1 is HIGH are motor1 and motor2, which do NOT suggest leds that can :"shin" brightly or dimly.

3

this part of code

if (L1 != stateON){
    if (L1 == HIGH){
      count++;
    }
        stateON = L1;
   if (L1 == HIGH){ 
    if (count % 2 == 0){
    digitalWrite(motor1, HIGH);
  }
  else{
    digitalWrite(motor2, HIGH);
  }}
4

What LEDs? We cannot guess where you've put them!

5

I made this code for regulating the water level, but before I tested (on bread board) putting the leds, and the I saw this effect that leds shin weaker then in the same loop when level 2 an level 3 is activated.

6

I'd guess that your diddling with the motorN pins far too often, making the LEDs that are connected to them act like PWM pins. You need to look at the state change detection example. You need to turn the motor(s) on when a switch BECOMES pressed, not when the switch IS pressed.