PHP echo cookie to console.log writing correctly in source but not in console

I have a PHP function that uses $_GET to grab ‘utm_source’ from the URL and set it in a cookie.

<?php
if(!isset($_COOKIE['utm_src'])) {
    $utm_src = $_GET['utm_source'];
    setcookie("utm_src", $utm_src, 0, "/");
}
?>

This all happens before any HTML is sent through (in functions.php using WordPress), and seems to be writing properly when I check the cookies after page load.

The issue occurs when I try to echo the variable into a javascript console.log in order to make sure everything is working properly:

<?php
$utm_src = $_COOKIE['utm_source'];
echo "<script>console.log('utm is $utm_src');</script>";
?>

The strange thing is that when I view source the script seems to be written correctly including the variable, yet not in the console.

This is what shows in the actual source after page load:

<script>
console.log('utm is utm-name-here');
</script>

However, the console only shows ‘utm is ‘, with no variable. I was hoping to use the cookie variable to determine whether a script should be echo’d onto page or not.