[SoftDeleteable] Remove dollar sign from cache key

Author: adambalint-srg

CHANGELOG.md

@@ -18,6 +18,8 @@ a release.
 ---
 
 ## [Unreleased]
+### Changed
+- All: Removed the dollar sign from the generated cache ID for extension metadata to ensure only characters mandated by [PSR-6](https://www.php-fig.org/psr/psr-6/#definitions) are used, improving compatibility with caching implementations with strict character requirements (#2978)
 
 ## [3.22.0] - 2025-12-13
 ### Added

src/Mapping/ExtensionMetadataFactory.php

@@ -181,7 +181,7 @@ public function getExtensionMetadata($meta)
      */
     public static function getCacheId($className, $extensionNamespace)
     {
-        return str_replace('\\', '_', $className).'_$'.strtoupper(str_replace('\\', '_', $extensionNamespace)).'_CLASSMETADATA';
+        return str_replace('\\', '_', $className).'__'.strtoupper(str_replace('\\', '_', $extensionNamespace)).'_CLASSMETADATA';
     }
 
     /**