Custom field value set to permalink only on new post, But they change it every time it's updated - wordpress

Question

I want to set the permalink slug using the custom field value for the first save only, but it is not working.
The code below changes the slug not only for the first save, but also for every update.
function custom_slug_auto_setting( $slug, $post_ID, $post_status, $post_type, $post_parent, $original_slug ) {
return $_POST['custom_field_title'];
}
add_filter( 'wp_unique_post_slug', 'custom_slug_auto_setting', 10, 6 );
For the second and subsequent saves, I want to keep the slug set for the first save.
I tried using the filter hook for wp_insert_post to specify post_name only for the first save, but that didn't work well either.
Is there any good solution?
Thank you.

Answer 1

save_post or save_post_{$post->post_type} Fires once a post has been saved. The dynamic portion of the hook name, {$post->post_type}, refers to the post type slug.
We need to discard any updates autosave or revision actions. The WordPress autosave system fire every 60 seconds.
#See https://wordpress.org/support/article/revisions/
The $update parameter is supposed to determined whether this is an existing post being updated. It applies more specifically to a post autosave revision. The $update parameter will always be true when firing through wp_publish_post. But that isn't true for its usage in wp_insert_post (See the following wordpress stackexchange answer and comments for more details...).
#See https://wordpress.stackexchange.com/a/185991/190376
In our case, the wp_publish_post function publish a post by transitioning the post status.
#See https://developer.wordpress.org/reference/functions/wp_publish_post/
By additionally crosschecking the post status we can effectively determine whether it is indeed a non-existing post.
If you are calling a function such as wp_update_post that includes the save_post hook, your hooked function will create an infinite loop. To avoid this, unhook your function before calling the function you need, then re-hook it afterward.
#See https://developer.wordpress.org/reference/hooks/save_post/#avoiding-infinite-loops
save_post will fire on post Update (eg: Autosave) or Publish which is why we're runing into an infinite loop.
#See https://wordpress.stackexchange.com/a/19539/190376
<?php
add_action( 'save_post', 'wpso74121743', 10, 3 ); //can be replaced by save_post_{$post->post_type}
if ( ! function_exists( 'wpso74121743' ) ) {
function wpso74121743( $post_id, $post, $update ) {
if ( ! wp_is_post_autosave( $post_id ) && ! wp_is_post_revision( $post_id ) && ! $update && $post->post_status == 'auto-draft' ) {
$override_post_name = sanitize_title( get_post_custom_values( 'custom_field_title', $post_id ), get_the_title( $post_id ) );
add_action( 'save_post', 'wpso74121743', 10, 3 ); //can be replaced by save_post_{$post->post_type}
wp_update_post( array(
'ID' => $post_id,
'post_name' => $self,
) );
add_action( 'save_post', 'wpso74121743', 10, 3 ); //can be replaced by save_post_{$post->post_type}
};
};
};