only update canonical

Author: lukeholder

CHANGELOG.md

@@ -3,7 +3,8 @@
 ## Unreleased
 
 - Fixed a bug where catalog pricing rules could generate promotional prices for non-promotable purchasables. ([#4118](https://github.com/craftcms/commerce/issues/4118))
-- Fixed a bug where variants weren’t duplicating correctly. ([#4125](https://github.com/craftcms/commerce/issues/4125))
+- Fixed a bug where variants weren't duplicating correctly. ([#4125](https://github.com/craftcms/commerce/issues/4125))
+- Fixed a bug where variant titles were being incorrectly updated when the Variant Title Format referenced the product. ([#4126](https://github.com/craftcms/commerce/issues/4126))
 - Fixed a SQL error that could occur when deleting a shipping method.
 
 ## 5.4.6 - 2025-09-04

src/elements/Product.php

@@ -1807,7 +1807,8 @@ public function beforeSave(bool $isNew): bool
     {
         $productType = $this->getType();
 
-        if (!$productType->hasVariantTitleField &&
+        if ($this->getIsCanonical() &&
+            !$productType->hasVariantTitleField &&
             $productType->variantTitleFormat &&
             StringHelper::containsAny($productType->variantTitleFormat, ['product.', 'owner.', 'primaryOwner.'])
         ) {