gw-merge-tag-modifier-url-encode.php

<?php
/**
 * Gravity Wiz // Gravity Forms // URL Encode Merge Tag Modifier
 * https://gravitywiz.com
 *
 * Use the :url_encode modifier on merge tags to URL encode the value
 *
 * this: Advanced Save & Continue
 * to:   Advanced+Save+%26+Continue
 */
 add_filter( 'gform_merge_tag_filter', function ( $value, $merge_tag, $modifier, $field, $raw_value, $format ) {
	
	if ( empty( $modifier ) ) {
		return $value;
	}

	$modifiers = array_map( 'strtolower', explode( ',', $modifier ) );
	if ( ! in_array( 'url_encode', $modifiers, true ) ) {
		return $value;
	}

	
    return urlencode( $value );
}, 10, 6 );