Detecting an incoming 7.875 kHz pulse to use as trigger
So i figured out what the problem was, I had to detach interrupts in the interrupt routines not in my main code. So basically these changes:
void loop() {
  digitalWrite(ledPin, LOW);
  attachInterrupt(digitalPinToInterrupt(pulse1), ISR_UV1, CHANGING);
  
}

&amp; in the Interrupt routines:
digitalWrite(ledPin, HIGH);      // Send high or Low dpending on the routine 
detachInterrupt(digitalPinToInterrupt(pulse1));

&amp; basically this works like a charm, &amp; there are still issues with the timer, but that will be solved in my main code with another sensor.