WordPress AJAX Function Hook

ajax_hook.php

<?php
/****** CUSTOM POST TYPE = 'SERVICES' HOOKS *******/
add_action( 'wp_ajax_get_client_timezone_info',   __NAMESPACE__ . '\\getTZInfo' );
add_action( 'wp_ajax_nopriv_get_client_timezone_info',   __NAMESPACE__ . '\\getTZInfo' );

add_filter( 'the_content',   __NAMESPACE__ . '\\replace_hello_with_good_morning' );

function replace_hello_with_good_morning($content){
    session_start();
    if(get_post_type()=='services'){
        echo "
        <script>
        var timezone_offset_minutes = new Date().getTimezoneOffset();
        timezone_offset_minutes = timezone_offset_minutes == 0 ? 0 : -timezone_offset_minutes;

        var data = {
            'action': 'get_client_timezone_info',
            'tom_inf': timezone_offset_minutes
            
        };
        var ajaxurl = '".admin_url('admin-ajax.php')."';
        
        jQuery.post(ajaxurl, data, function(response) {
            console.log(response);
        });
        </script> ";

        $utz_name = $_SESSION['utz_name'];
        $utz_hour = $_SESSION['utz_hour'];
        if($utz_hour <= 12){
            $content = str_ireplace("Hello", "Good Morning", $content);
        }

        return $content;
    }
}

function getTZInfo(){
    session_start();
    global $wpdb;
    
    $tom_inf = $_POST['tom_inf'];

    $timezone_offset_minutes = $tom_inf;

    // Convert minutes to seconds
    $timezone_name = timezone_name_from_abbr("", $timezone_offset_minutes*60, false);

    $_SESSION['utz_name'] = $timezone_name;
    date_default_timezone_set($timezone_name);
    // 24-hour format of an hour without leading zeros (0 through 23)
    $Hour = date('G');

    $_SESSION['utz_hour'] = $Hour;

    echo "  ". date("d-m-Y H:i:s ")."    ";


    //echo $_SESSION['utz_name']. " | " . $timezone_name;
}