How to know number of Nights spent given night start and end times in PHP

I have this method that should calculate the no of nights spent in parking given the

1. Check-in date and time.
2. Check-out date and time.
3. Night Start time.
4. Night end time.

This is the far I have gotten and then I was like, what next?

public function getNightsSpent()  {

   $dateCheckin = new Carbon('2022-08-25 17:23:22');
        $dateCheckout = new Carbon('2022-08-27 10:35:18');

        $checkInTime = new Carbon($dateCheckin->format('H:i:s'));
        $checkOutTime = new Carbon($dateCheckout->format('H:i:s'));


        $nightStart = new Carbon('23:00:00');
        $nightEnd = new Carbon('06:00:00');

        $nightHours = $nightStart->diffInRealHours($nightEnd);

        $dayMinutesBeforeFirstNightStart = $nightStart->diffInMinutes($checkInTime);
        $dayMinutesAfterLastNightEnd = $checkOutTime->diffInMinutes($nightEnd);

        $dayMinutesInBothEnds = $dayMinutesBeforeFirstNightStart + $dayMinutesAfterLastNightEnd;
        $dayHoursInBothEnds = $dayMinutesInBothEnds/60;

        $totalHoursSpent = $dateCheckout->diffInHours($dateCheckin);

        return ($totalHoursSpent - $dayHoursInBothEnds)/$nightHours;
}

Note: I have hard-coded dates and times for easier reference.

For this am getting the answer as 1.8 but when I introduce a different no say check-in be 2022-08-20 it is giving me 8.8 nights which is not correct.

I am using Laravel 9 and PHP8.1