Generating Unique User ID after Registration

WordPress already creates a unique ID for each users at registration.

Create a shortcode using the uwp_get_displayed_user() function and add it to your profile via Form Builder > Profile Tabs

I asked ChatGPT to do this and it knocked it out of the park:

1 Install the Code Snippet plugin and create a new snippet with the following code or add it to functions.php of your child theme:

function output_uwp_user_id() {
    // check if we are on a UsersWP profile page
    if (function_exists('uwp_get_displayed_user')) {
        // get the user being displayed
        $displayed_user = uwp_get_displayed_user();

        // if a user is found, return the ID
        if (!empty($displayed_user->ID)) {
            return $displayed_user->ID;
        } else {
            return "No user found.";
        }
    } else {
        // return an error message if we are not on a UsersWP profile page
        return "This shortcode only works on UsersWP profile pages.";
    }
}
add_shortcode('uwp_user_id', 'output_uwp_user_id');

add the shortcode to a new tab or nest the new tab inside an existing tab

[uwp_user_id]

I tested it and it works flawlessly.