Do comparision after updates hooks of acf-fields?

ACF launches these hooks on the hook save_post then you can compare values just before like that :

add_action("save_post", function ($post_ID, \WP_Post $post, bool $update) {

    // read old values with get_post_meta($post_id, "bookitall_fromdate", TRUE) ...

    // read new values in $_POST


    // do action if the 2 dates are changed



}, 6, 3); // priority 6 for launching before ACF saving with priority 10