Compatibility Plugin
Developer Note
Heads-up, don't create a plugin as behaviour plugin because it's possible that this group get removed at some point.
Joomla 5 Compatibility Plugin
As part of Joomla! 5.0 a plugin was introduced which enhance backward compatibility between Joomla 5 and 4. The plugin is implemented as "Behaviour" plugin type to guarantee that is loaded before any other plugin is loaded.
For more detail check Compatibility Plugin Joomla! 5.0.