Conflict with Easy Footnotes

The technical explanation of the problem is that it occurs when tags are used within an attribute (like title). I don’t know a good way to solve that problem.

A workaround in your case, could be adding this code to the functions.php file of your active theme:

add_action( 'wpel_before_apply_link', function ( $link ) {
    $easy_footnote_url = '#easy-footnote';

    // ignore easy footnote links
    if ( false !== strpos( $link->get_attr( 'href' ), $easy_footnote_url ) ) {
        $link->set_ignore();
    }
}, 10, 1 );