Font awesome preload warning when Django app deployed to Heroku, but not on dev server

It’s my first day using heroku to deploy my Django app.

When I deploy my Django app on Heroku, the chrome inspector gives this warning:

The resource https://ka-f.fontawesome.com/releases/v6.6.0/webfonts/free-fa-solid-900.woff2 was preloaded using link preload but not used within a few seconds from the window’s load event. Please make sure it has an appropriate as value and it is preloaded intentionally.

When I click the warning link it shows the first line of my index page html, which is blank.

I don’t get this warning when running in my development server and setting the Django project Debug mode has no effect.

I have deleted every mention of fontawesome in my project including removing the fontawesome reference from the head of my base.html and removing it from my installed apps etc., but I still receive this warning. I used search to double check there were no font awesome references. Have tried to look up solutions for several hours today and am stumped.

My base.html page looks like this:

{% load static %}

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Dotstory</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <link rel="shortcut icon" type="image/x-icon" href="{% static 'storymode/images/favicon.png' %}"/>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
  </head>

and my index looks like this:

{% extends "base.html" %}

{% block content %}
<h1>n</h1>
    <main class="text-center mt-20" id="game">
        <h1 class="mb-4">This is the Main Page</h1>
            {% for story in stories %}
                <a href="/story/{{story.pk}}"><h1>{{story.title}}, {{story.pk}}</h1></a>
                <br>
            {% endfor %}
    </main>
{% endblock content %}

[EDIT]: To add to the mystery, when I re-add my script to connect my font-awesome kit in the html head: <script src="https://kit.fontawesome.com/fe9b6298ed.js" crossorigin="anonymous"></script>

And re-deploy the project to heroku, I receive the following error in addition to the one above: A preload for ‘https://ka-f.fontawesome.com/releases/v6.6.0/webfonts/free-fa-solid-900.woff2’ is found, but is not used because the request credentials mode does not match. Consider taking a look at crossorigin attribute.

So it seems that despite my attempts to delete all fontawesome references, it is still being searched for?