WordPress shortcode returns the data before

Change form.php

<form action="<?= $_SERVER["REQUEST_URI"]; ?>" method="post">
     <input type="hidden" name="form_submit_nonce" value="<?php echo wp_create_nonce('form-submit-nonce'); ?>"/>
     <label for="id">ID</label>
     <input id="id" name="id" type="text" value="" required />
     <input type="submit" name="submitid" value="Submit">
   </form>

Change plugin file

function form_shortcode(){
    
      if ( isset( $_POST["submitid"] ) && isset($_POST['form_submit_nonce'])  && wp_verify_nonce($_POST['form_submit_nonce'], 'form-submit-nonce') ) {
            echo "<p>OK</p>";
      } else {
        
            include "form.php";
      }
}
add_shortcode( "form", "form_shortcode" );