wp replace publish – wp_update_post altering into unicode

I’ve run into a problem I have not confronted earlier than so I am hoping somebody could have a solution or answer.

I am an updating a number of posts on the identical time with wp_update_post with a string worth of This can be a piece of <em>string</em> for example. The code is as follows:

foreach ( $aposts as $spost ) {
    $post_id = $spost->ID;
    $content material = $spost->post_content;
    
    $newcontent = preg_replace( $regex, $replace_string, $content material );
    
    $revcontent = array( 'ID' => $post_id, 'post_content' =>$newcontent, );

    $ppost = wp_update_post( $revcontent );
}

It loops by means of the posts and modifications the content material. Nevertheless if the content material is wrapped with <em></em>, it is changed with unicode characters e.g. u003cu003eThis is a bit of stringu003cu003eu003e.

If I replace the content material inside WordPress admin by clicking on “Replace”, the content material modifications as meant with <em></em> intact. Unfiltered HTML is enabled.