Problem on multiple interrupts operation on Arduino Uno
You are being way way too convoluted with this. You're overthinking it.

The code should be as simple as (LED stuff omitted):

volatile bool running = false;
const uint8_t switch1 =3;
const uint8_t switch2 =2;

void setup() {
    pinMode(switch1, INPUT_PULLUP);
    pinMode(switch2, INPUT_PULLUP);
    attachInterrupt(digitalPinToInterrupt(switch1), turnOn, FALLING);
    attachInterrupt(digitalPinToInterrupt(switch2), turnOff, FALLING);
}

void loop() {
    if (running) {
        // Do something
    } else {
        // Do something else
    }
}

void turnOn() {
    running = true;
}

void turnOff() {
    running = false;
}


Note that what goes in loop() should be non-blocking, or at least have a reasonably short duration, so that it is able to pick up the changed running variable.

However, for something like this, interrupts are pretty pointless.