Make First Name, Last Name and a custom field read-only for non-admin users

my_pmpro_member_read_only_fields_js.php

<?php
/**
 * This recipe assigns the readonly attribute to the fields
 * first_name, last_name, and date_de_naissance on profile edit pages
 * for non-admin users.
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

/**
 * Output the JS to make fields readonly for non-admins.
 */
function my_pmpro_member_read_only_fields_js() {
	// Bail if admin or not logged in user.
	if ( ! is_user_logged_in() || current_user_can( 'manage_options' ) ) {
		return;
	}

	?>
	<script>jQuery(document).ready(function ($) {
		$('#first_name').attr('readonly', true);
		$('#last_name').attr('readonly', true);
		$('#date_de_naissance').attr('readonly', true);
	});	</script>
	<?php
}

/**
 * Add the readonly field JS to the backend profile update page.
 */
function my_pmpro_wp_profile_update_readonly_fields() {
	// We're on the WP Dashboard but not an admin.
	global $pagenow;
	if ( is_admin() && 'profile.php' === $pagenow ) {
		add_action( 'admin_footer', 'my_pmpro_member_read_only_fields_js' );
	}
}
add_action( 'init', 'my_pmpro_wp_profile_update_readonly_fields' );

/**
 * Add the readonly field JS to the frontend Member Profile Edit page.
 */
function my_pmpro_member_profile_edit_readonly_fields() {
	// Bail if PMPro Core not active.
	if ( ! defined( 'PMPRO_VERSION' ) ) {
		return;
	}
	// We're on the front end profile edit page.
	global $pmpro_pages;
	if ( is_page( $pmpro_pages['member_profile_edit'] ) ) {
		add_action( 'wp_footer', 'my_pmpro_member_read_only_fields_js' );
	}
}
add_action( 'wp', 'my_pmpro_member_profile_edit_readonly_fields' );