Invalid timezone

My site health was reporting a critical error with an invalid timezone:

PHP default timezone was changed after WordPress loading by a date_default_timezone_set() function call. This interferes with correct calculations of dates and times.

The cause was traced back to the Countdown Timer plugin. Commenting out lines 147–150 of fergcorp_countdownTimer.php fixed the issue:

		$tz = get_option('timezone_string');
		if ( $tz ){ //Get and check if we have a valid time zone...
			date_default_timezone_set($tz); //...if so, use it
		}

This was in a PHP 8.3 environment.