Joomla! 4.0 is a special version which introduces a new timebased release cycle. This cycle allow us to remove old code every 2 years. Based on motion PROD2022/011 we keep deprecations for at least one major version. For this we retagged all deprecation which are introduced in 4.0 with version 4.3. That means we don't have many deprecations left for 4.0 and you can find all relevant deprecations introduced in 4.0 at 4.3 deprecations.