diff --git a/modules/ModuleBuilder/parsers/StandardField.php b/modules/ModuleBuilder/parsers/StandardField.php
index ac882424978..1006e9b79ef 100755
--- a/modules/ModuleBuilder/parsers/StandardField.php
+++ b/modules/ModuleBuilder/parsers/StandardField.php
@@ -8,7 +8,7 @@
  * SugarCRM, Inc. Copyright (C) 2004-2013 SugarCRM Inc.
  *
  * SuiteCRM is an extension to SugarCRM Community Edition developed by SalesAgility Ltd.
- * Copyright (C) 2011 - 2018 SalesAgility Ltd.
+ * Copyright (C) 2011 - 2024 SalesAgility Ltd.
  *
  * This program is free software; you can redistribute it and/or modify it under
  * the terms of the GNU Affero General Public License version 3 as published by the
@@ -119,17 +119,19 @@ public function addFieldObject(&$field)
         $this->baseField = get_widget($field->type) ;
         foreach ($field->vardef_map as $property => $fmd_col) {
             if ($property == "action" || $property == "label_value" || $property == "label"
-                || ((substr((string) $property, 0, 3) == 'ext' && strlen((string) $property) == 4))
+                || ((str_starts_with((string)$property, 'ext') && strlen((string) $property) == 4))
+                // possible bug here...  $property is often the same as $fmd_col, but not always. Maybe we should also add:
+                // || ((str_starts_with((string)$fmd_col, 'ext') && strlen((string) $fmd_col) == 4))
+                // ... but a thorough analysis of the consequences of this would be required.
             ) {
                 continue;
             }
-                   
-            // Bug 37043 - Avoid writing out vardef defintions that are the default value.
+
+            // Avoid writing out vardef definitions that are the default value, when possible.
+            // Since isDefaultvalue() is quite limited, and doesn't handle all cases well,
+            // sometimes we won't detect defaults and will store them anyway.
             if (isset($newDef[$property]) &&
-                (
-                    (!isset($currdef[$property]) && !$this->isDefaultValue($property, $newDef[$property], $this->baseField))
-                    || (isset($currdef[$property]) && $currdef[$property] != $newDef[$property])
-                )
+                !$this->isDefaultValue($property, $newDef[$property], $this->baseField)
             ) {
                 $this->custom_def[$property] =
                     is_string($newDef[$property]) ? htmlspecialchars_decode($newDef[$property], ENT_QUOTES) : $newDef[$property];