HTML Content and PHP Echo Not Displaying in WordPress Page

Website: https://www.Warehouse-HourlyShifts.com
Wordpress Version: 5.5.3
Php Version: 5.6
Browsers: Chrome and Edge
I have this simple PHP file that is being executed from a WordPress Page:
*************************************
<?php
$to = “BLOCKED [email protected]”;
$subject = “Test PHP”;
$message = “from test-php page”;

$headers = ‘From: [email protected]’ . “\r\n” .
‘X-Mailer: PHP/’ . phpversion();
mail($to, $subject, $message, $headers, ‘[email protected]’);
?>
<p> html display in testphp.php </p>

<?php
echo “echo display in testphp.php”;

*******************************************
I AM receiving the text message from the PHP file so I know this PHP file is being executed from the WordPress Page.

The problem is when I execute this PHP file directly from a WordPress page (test-php) I am not seeing the HTML content between the <p> and </p> tags nor am I seeing the echo statement content. However, when I execute this PHP file directly from the URL line instead of from within a WordPress page it is working fine.

When I execute this same PHP file from a WordPress page in other WordPress websites that I have the displays are working fine. The WordPress version for a site that is displaying correctly is 5.9.5 and the PHP Version is 5.6

There must be some configuration set or not set in the WordPress of the problem website that is causing the displays not to work, but I can’t figure out what it is.

https://www.Warehous-HourlyShifts.com/test-php This is the website and page not working
https://www.MainEventSocialClub.com/test-php This is the website and page that is Working – Both websites have the same PHP plugin that enables executing PHP code from a Page

Any help would be greatly appreciated.

The page I need help with: [log in to see the link]