Using HardwareSerial with Mega 2560 extra serial pins (Bluetooth/servo conflict)

Using Arduino Programming Questions
4

The extra serial ports have their own pins. The use of those ports will not interfere with regular Serial (USB) or the Servo library.

Then i have an entierly different problem.
Here's whats happening,Whenever i write to the servo while bluetooth is connected(eg:section A in the code), the my phone disconnects to the connection to the bluetooth, and i have to reconnect again, The first command i send works , then the phone disconnects, heres a code:

#include <Servo.h>
#include <HardwareSerial.h>
Servo FlameServo;
void setup() {
  // put your setup code here, to run once:
    Serial1.begin(9600); //bluetooth
  FlameServo.attach(35);
  FlameServo.write(0); //servo
  Serial.begin(19200); 
}
char state;
int x,y;
void loop() {
  
while (Serial1.available()) {
      state = Serial1.read();
      if (state == 'A') { //servo left
        delay(5);
        if (Serial1.read() == '#') {
            FlameServo.write(90);    //command runs, but bluetooth disconnects after this,
            delay(100);
        }
      }
      if (state == 'S') { //spray water
        delay(5);
         
        if (Serial1.read() == '#')
        Serial.println("Spra");
      }
      if (state == 'D') { //Servo Right
        delay(5);
        if (Serial1.read() == '#'){
          Serial.println("d");
            FlameServo.write(180);   //command runs, but bluetooth disconnects after this,
delay(100);
        }
      }
     
      delay(5);
    }
  }

Juraj:
what library?

I think I misunderstood the problem, i was talking about teh HardwareSerial libary, but I dont think using that would help, im guessing the problem is with the app im using? its this:https://play.google.com/store/apps/details?id=com.nudge.me.JSF