This code will filter ACF fields added to custom templates using the post's membership requirements.

pmpro-hide-acf-fields.php

<?php
/**
 * pmpro_hide_acf_fields This code will filter ACF fields added to custom templates using the post's membership requirements.
 *
 * Add this code to your PMPro Customizations Plugin
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 *
 * https://www.advancedcustomfields.com/resources/acf-format_value/
 *
 * @param  mixed $value   Value which was loaded from the database
 * @param  mixed $post_id Post ID value was loaded from
 * @param  array $field   Array containing all the field settings for the field which was used to upload the attachment
 *
 * @return mixed          Returned value if member has access
 */
function pmpro_hide_acf_fields( $value, $post_id, $field ) {
	// Check if the user has access to the post.
	$hasaccess = pmpro_has_membership_access( $post_id );
	if ( empty( $hasaccess ) ) {
		// If user does not have acces to the post, empty the field value.
		$value = '';
	}

	// return
	return $value;
}
add_filter( 'acf/format_value', 'pmpro_hide_acf_fields', 10, 3 );