What potential issue could arise from the incorrect time calculation in the code?

If the time calculation in the code is incorrect, it could lead to inaccurate results or unexpected behavior in the application. This could affect any functionality that relies on time calculations, such as scheduling tasks, displaying timestamps, or time-sensitive operations. To solve this issue, it is important to ensure that the time calculations in the code are accurate and properly handle time zones if necessary.

// Incorrect time calculation
$start_time = strtotime('2022-01-01 10:00:00');
$end_time = strtotime('2022-01-01 12:00:00');
$duration = $end_time - $start_time;

// Corrected time calculation with timezone set to UTC
date_default_timezone_set('UTC');
$start_time = strtotime('2022-01-01 10:00:00');
$end_time = strtotime('2022-01-01 12:00:00');
$duration = $end_time - $start_time;