how to add value off input into table?

I have successfully added the custom taxonomy for employer tags to the employer table. However, I am currently unable to retrieve and save the values from the input field on the meta box. As of now, tags can only be added manually through the WordPress dashboard. I attempted the following code to resolve this issue, but it did not work as expected.
this is the input:

<input type="text" class="regular-text" name="tag" id="tag" value="" placeholder="tag1, tag2, tag3"'/>

function create_employer_custom_taxonomy() {    
    $labels = array(
        'name'              => _x('Employer Tags', 'taxonomy general name', 'textdomain'),
        'singular_name'     => _x('Employer Tag', 'taxonomy singular name', 'textdomain'),
        'search_items'      => __('Search Employer Tags', 'textdomain'),
        'all_items'         => __('All Employer Tags', 'textdomain'),
        'parent_item'       => __('Parent Employer Tag', 'textdomain'),
        'parent_item_colon' => __('Parent Employer Tag:', 'textdomain'),
        'edit_item'         => __('Edit Employer Tag', 'textdomain'),
        'update_item'       => __('Update Employer Tag', 'textdomain'),
        'add_new_item'      => __('Add New Employer Tag', 'textdomain'),
        'new_item_name'     => __('New Employer Tag Name', 'textdomain'),
        'menu_name'         => __('Employer Tags', 'textdomain'),
    );
    $args = array(
        'hierarchical'      => false,
        'labels'            => $labels,
        'show_ui'           => true,
        'show_admin_column' => true,
        'update_count_callback' => '_update_post_term_count',
        'query_var'         => true,
        'rewrite'           => array('slug' => 'employer_tag'),
    );
    register_taxonomy('employer_tag', 'employer', $args);
}
add_action('init', 'create_employer_custom_taxonomy');

function add_employer_tags_meta_box() {
    add_meta_box(
        'employer_tags_meta_box',
        'Employer Tags',
        'employer_tags_meta_box_callback',
        'employer', // Post type
        'normal',
        'high'
    );
}
add_action('add_meta_boxes', 'add_employer_tags_meta_box');

function employer_tags_meta_box_callback($post) {
    wp_nonce_field('save_employer_tags_meta_box_data', 'employer_tags_meta_box_nonce');
    $tags = wp_get_post_terms($post->ID, 'employer_tag', array('fields' => 'names'));
    $tags_string = implode(', ', $tags); // Convert array to comma-separated string
    echo '<div class="cmb-td">';
    echo '<input type="text" class="regular-text" name="tag" id="tag" value="' . esc_attr($tags_string) . '" placeholder="Tag1, Tag2, Tag3" />';
    echo '</div>';
}


function save_employer_tags_meta_box_data($post_id) {
    if (!isset($_POST['employer_tags_meta_box_nonce'])) {
        return;
    }
    if (!wp_verify_nonce($_POST['employer_tags_meta_box_nonce'], 'save_employer_tags_meta_box_data')) {
        return;
    }
    if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) {
        return;
    }
    if (!current_user_can('edit_post', $post_id)) {
        return;
    }

    if (isset($_POST['tag'])) {
        $tags = sanitize_text_field($_POST['tag']);
        // Split tags by comma and trim whitespace
        $tags_array = array_map('trim', explode(',', $tags));
        // Save tags to the custom taxonomy
        if (!empty($tags_array)) {
             foreach ($tags_array as $tag) {
                if (!term_exists($tag, 'employer_tag')) {
                    wp_insert_term($tag, 'employer_tag');
                }
            }
            wp_set_post_terms($post_id, $tags_array, 'employer_tag', false);
        } 
    }
}
add_action('save_post', 'save_employer_tags_meta_box_data');

function display_employer_tags() {
    global $post;
    $tags = wp_get_post_terms($post->ID, 'employer_tag');
    if (!empty($tags)) {
        echo '<div class="employer-tags">';
        echo '<h3>Tags:</h3>';
        echo '<ul>';
        foreach ($tags as $tag) {
            echo '<li>' . esc_html($tag->name) . '</li>';
        }
        echo '</ul>';
        echo '</div>';
    }
}
add_action('freeio_single_employer_after', 'display_employer_tags');