Move the JPATH_PLATFORM constant to the compat plugin

migrations/54-60/compat-plugin.md

@@ -19,3 +19,15 @@ The plugin is implemented as "Behaviour" plugin type to guarantee that is loaded
 For more detail check [Compatibility Plugin Joomla! 5.0](https://manual.joomla.org/migrations/44-50/compat-plugin).
 
 
+### JPATH_PLATFORM constant
+
+- PR: https://github.com/joomla/joomla-cms/pull/44638
+- File: All bootstrapping files
+- Description: The `JPATH_PLATFORM` is an old constant and should not be used if the Joomla core got correctly bootstrapped. Change your checks to `_JEXEC`
+```php
+// Old:
+\defined('JPATH_PLATFORM') or die;
+
+// New:
+\defined('_JEXEC') or die;
+```