Update a text field in a block when saving a post?

I’m updating my theme to work with Gutenberg and I’m having a problem updating a text field in a block when saving a post.

In my old theme, I had a function that updated a text field in a metabox when saving a post using update_post_meta. It takes the data in a text field and updates it to something else. I tried to do the same for a block but it didn’t update.

Is there a way to update a text field in a block using update_post_meta when saving a post?

Here’s my code:

// function
function post_extra_save( $post_id, $post){

// get blocks
if ( has_blocks( $post->post_content ) ) {
    $blocks = parse_blocks( $post->post_content );
    foreach ( $blocks as $block ) {
        // the block
        if ( $block['blockName'] === 'acf/opby-video' ) {
            // extract the data from the text field and separate it using explode
            $media_video_url = explode('/', $block['attrs']['data']['youtube_url']);
            // if explode matches
            if ($media_video_url[2] == 'www.youtube.com') {
                $new_vid_embed_2_raw = str_replace("watch?v=","",$media_video_url[3]);
                $new_vid_embed_2_check = 'https://www.youtube.com/watch?v='.$new_vid_embed_2_raw;
                $new_vid_embed_2 = 'https://www.youtube.com/embed/'.$new_vid_embed_2_raw;
                // update the text field when saving
                if ($new_vid_embed_2 && get_post_meta( $post->ID, 'youtube_url', true ) !== $new_vid_embed_2_check) {
                    update_post_meta( $post->ID, 'youtube_url', $new_vid_embed_2 );
                }
            };
        }
    }
};
}
add_action( 'save_post', 'post_extra_save', 10, 2 );