I have been working on this project where the ESP32 connects to a web server and sends it the measurements from the Ultra Sonic sensor.
Before starting the project, I tested the sensor alone with this dummy code:

/*
 * HC-SR04 example sketch
 */

const int trigPin = 4;
const int echoPin = 2;
const int ledPin = 0;
bool ledState = false;

float duration, distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT); 
  Serial.begin(115200);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = (duration*.0343)/2;

  if (distance < 50 && !ledState){
    Serial.println("ON");
    ledState = true;
    digitalWrite(ledPin, HIGH);
  } else if (distance > 50 && ledState){
    Serial.println("OFF");
     ledState = false;
    digitalWrite(ledPin, LOW);
  }
  Serial.print("Distance: ");
  Serial.println(distance);
  delay(2000);
}

And all seemed to be working fine.
In the final project, readings become unstable and without any sense.
I started brainstorming and though about testing the dummy code, but with Wi-Fi connection:

/*
 * HC-SR04 example sketch
 *
 * https://create.arduino.cc/projecthub/Isaac100/getting-started-with-the-hc-sr04-ultrasonic-sensor-036380
 *
 * by Isaac100
 */

 #include <WiFi.h>

const int trigPin = 4;
const int echoPin = 2;
const int ledPin = 0;
bool ledState = false;

// WIFI LOGIN
const char* ssid = "**";
const char* password = "**";
float duration, distance;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT); 
  Serial.begin(115200);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = (duration*.0343)/2;

  if (distance < 50 && !ledState){
    Serial.println("ON");
    ledState = true;
    digitalWrite(ledPin, HIGH);
  } else if (distance > 50 && ledState){
    Serial.println("OFF");
     ledState = false;
    digitalWrite(ledPin, LOW);
  }
  Serial.print("Distance: ");
  Serial.println(distance);
  delay(2000);
}

And I am now encountering the same exact problem, nonsense unstable readings.

Anyone has an idea on what may be causing the problem? I have tried reading the voltage with a Multimeter, but the voltage seems to be the same in the two cases. I also considered Wi-Fi interference with the readings, but I don’t really think that’s the case.