Adjust the .elementor-background-overlay element with a PHP filter to add the role="img" attribute for accessibility purposes.

wp-elementor-overlay-wcag.php

<?php
add_filter( 'elementor/frontend/the_content', 'MYPREFIX_add_role_to_elementor_overlay' );
/**
 * Find the <div class="elementor-background-overlay"></div> element and add the role="img" attribute
 * to meet accessibility guidelines.
 *
 * @since 1.0.0
 *
 * @param $content
 * @return string
 */
function MYPREFIX_add_role_to_elementor_overlay($content) {
    $content = str_replace('<div class="elementor-background-overlay">', '<div class="elementor-background-overlay" role="img">', $content);
    return $content;
}