In case anyone else needs a solution to this specific issue, here is what worked to hide the nag.
I added this small snippet of code to my Child Theme’s functions.php file:
add_filter( 'acf/admin/prevent_escaped_html_notice', '__return_true' );
If you use this, please be sure to FIRST check your usage of (ACF’s) the_field, which now escapes any HTML in the contents of the_field, and ensure that you won’t have any site-breaking issues.
