Adding font awesome icons

Hi,
How can I add font awesome icons to the Reading Time prefix without the plugin manipulating the HTML?

When I add this:

<i class=”fas fa-stopwatch”></i>

The plugin changes it to:

<i class=\”fas fa-stopwatch”\></i>

I have Scripts and Styles as well as Child Theme Configurator Plug-ins should these tools help to work around the limitation.

Thanks for help!

Steve