Moving post title down the page / Removing a block from a post

The solution is/was simple. Use a priority of 1 in the add_filter() function.

function carousel_block_remover( $content ) {
    // Matches <!-- wp:client/carousel {"id":"100"} /-->
    $regex = '/<!-- wp:client\/carousel {"id":"(.*)"} \/-->/';

    if ( preg_match( $regex, $content ) ) {
        // Filter the first block out of the_content
        $content = preg_replace( $regex, '', $content, 1);
    }
    return $content;
}
add_filter( 'the_content', 'carousel_block_remover', 1 );