How can I create a WPFORMS unique ID smart tag showing incremental numbers starting from 100?

Question

I would like to create a smart tag to show a unique ID for each form entry. I want the Unique ID to be sequential numbers starting from 100. For each subsequent form entry submitted, the unique ID number should be incremented by 1.

I have researched and come across this WPforms article: https://wpforms.com/developers/how-to-create-a-unique-id-for-each-form-entry/ But it does not cover sequential numbers.

I tried the following code from https://wpforms.com/developers/how-to-create-a-unique-id-for-each-form-entry/

/*
 * Create a unique ID with a specific number of characters and assign it to each form submission.
 *
 * @link https://wpforms.com/developers/how-to-create-a-unique-id-for-each-form-entry/
 */
 
// Generate Unique ID Smart Tag for WPForms
function wpf_dev_register_smarttag( $tags ) {
 
    // Key is the tag, item is the tag name.
    $tags[ 'unique_id' ] = 'Unique ID';
 
    return $tags;
}
 
add_filter( 'wpforms_smart_tags', 'wpf_dev_register_smarttag' );
 
// Generate Unique ID value
function wpf_dev_process_smarttag( $content, $tag, $form_data, $fields, $entry_id ) {
           
    // Only run if it is our desired tag.
    if ( 'unique_id' === $tag && !$entry_id ) {
         
    // Start at 100
    // increment by 1
    $uuid = 100;
    $uuid++;    
        // Replace the tag with our Unique ID.
        $content = str_replace( '{unique_id}', $uuid, $content );
    } elseif ( 'unique_id' === $tag && $entry_id ) {
         
        foreach ($form_data[ 'fields' ] as $field) {
             
            if ( preg_match('/\b{unique_id}\b/', $field[ 'default_value' ]) ) {
                $field_id = $field[ 'id' ];
                break;
            }
             
        }
         
        $content = str_replace( '{unique_id}', $fields[$field_id][ 'value' ], $content);
    }
   
    return $content;
}
   
add_filter( 'wpforms_smart_tag_process', 'wpf_dev_process_smarttag', 10, 5 );

I keep getting 101 with each form submission. What am I doing wrong?