Parse Error in Production and Not Local Server

Hello. I'm new to the forum but not new to CI. Been a user since CI3. I just downloaded a fresh copy of CI and developed a starter site in WAMP. All was working great; pushed it over to production server and it wont load. The server error log says:

Error Log Excerpt

Code:

[12-Oct-2021 14:45:24 America/Chicago] PHP Parse error:  syntax error, unexpected ':', expecting '{' in /mysite/system/Common.php on line 44

System/Common.php Excerpt

Code:

if (! function_exists('app_timezone')) {
    /**
    * Returns the timezone the application has been set to display
    * dates in. This might be different than the timezone set
    * at the server level, as you often want to stores dates in UTC
    * and convert them on the fly for the user.
    */
    function app_timezone(): string    /**Line 44*/
    {
        $config = config(App::class);

        return $config->appTimezone;
    }
}

Just as the CI user's guide says, I did not modify any sys files.

Anyone run into the same issue?  I researched a bit but never found anything. Any/all help on this would be greatly appreciated. [/code]