I am blinking an LED on PORTB5 using timer 0 in mode 7. The time between blinks is computed as $$ \frac{(\text{OCROA}+1) \times \text{prescaler} \times \text{timerCount}}{\text{FCPU}} $$ \$FCPU=16MHz\$. With \$OCROA=124\$, \$prescaler=1024\$, and \$timerCount=125\$, the time turns out to be \$1 \space second\$ and this works as expected. But with \$OCROA=16\$, \$prescaler=1\$, and \$timerCount=2956793\$, I would expect the time to be \$~3.14 \space seconds\$, but I am getting something around \$12 \space seconds\$.

Code that works as expected:

    #include <avr/interrupt.h>
    #include <stdint.h>
    
    volatile uint32_t timerCount = 0;
    ISR(TIMER0_COMPA_vect)
    {
            ++timerCount;
    }
    
    int main(void)
    {
            DDRB |= 1 << DDB5;
            TIMSK0 |= 1 << OCIE0A;
            TCCR0A |= 1 << WGM00 | 1 << WGM01;
            TCCR0B |= 1 << WGM02;
            OCR0A = 124;
            sei();
            TCCR0B |= 1 << CS02 | 1 << CS00;
            while(1)
            {
            if(timerCount >= 125)
                    {
                            PORTB ^= 1 << PORTB5;
                            timerCount = 0;
                    }
            }
            return 0;
    }

Code that  does not work as expected:

    #include <avr/interrupt.h>
    #include <stdint.h>
    
    volatile uint32_t timerCount = 0;
    ISR(TIMER0_COMPA_vect)
    {
            ++timerCount;
    }
    
    int main(void)
    {
            DDRB |= 1 << DDB5;
            TIMSK0 |= 1 << OCIE0A;
            TCCR0A |= 1 << WGM00 | 1 << WGM01;
            TCCR0B |= 1 << WGM02;
            OCR0A = 16;
            sei();
            TCCR0B |= 1 << CS00;
            while(1)
            {
            if(timerCount >= 2956793)
                    {
                            PORTB ^= 1 << PORTB5;
                            timerCount = 0;
                    }
            }
            return 0;
    }

What could be the issue with the latter?