Only save posted settings to PC

Fixes craftcms/commerce#4006

Author: brandonkelly

CHANGELOG.md

@@ -1,6 +1,10 @@
 # Release Notes for Craft CMS 4
 
-## 4.16.17 - 2025-12-04
+## Unreleased
+
+- Fixed a bug where all plugin settings were being saved to the project config, rather than just posted settings. ([craftcms/commerce#4006](https://github.com/craftcms/commerce/issues/4006))
+
+## 4.16.17 - 2025-12-0421
 
 - Fixed a bug where remove buttons within multi-select Selectize inputs weren’t working if the input wasn’t focusend and fully in view. ([#18079](https://github.com/craftcms/cms/issues/18079))
 - Fixed an error that could occur when executing a GraphQL mutation when the `lazyGqlTypes` config setting was enabled. ([#18014](https://github.com/craftcms/cms/issues/18014))

src/services/Plugins.php

@@ -744,7 +744,9 @@ public function savePluginSettings(PluginInterface $plugin, array $settings): bo
 
         // Update the plugin’s settings in the project config
         $pluginSettings = $plugin->getSettings();
-        $pluginSettings = $pluginSettings ? ProjectConfigHelper::packAssociativeArrays($pluginSettings->toArray()) : [];
+        $pluginSettings = $pluginSettings
+            ? ProjectConfigHelper::packAssociativeArrays($pluginSettings->toArray(array_keys($settings)))
+            : [];
         Craft::$app->getProjectConfig()->set(ProjectConfig::PATH_PLUGINS . '.' . $plugin->handle . '.settings', $pluginSettings, "Change settings for plugin “{$plugin->handle}”");
 
         $plugin->afterSaveSettings();