The reason that the open source nature of Unreal Engine 4 and 5 does not lead to confidentiality issues with console game development is that Epic Games, the company behind Unreal Engine, has strict licensing agreements in place to prevent any such violations.
When developers use Unreal Engine to create games for consoles such as PS4, NS, and Xbox, they must obtain a license from Epic Games and agree to the terms and conditions of the license agreement. These terms and conditions include strict guidelines on how the engine can be used, including limitations on what can be shared publicly and how proprietary information must be handled.
In addition, Epic Games has a dedicated team that works closely with console manufacturers such as Nintendo, Sony, and Microsoft to ensure that their licensing agreements are followed, and that any confidential information is handled appropriately.
Therefore, the open-source nature of Unreal Engine does not pose a risk to confidentiality, as long as developers follow the terms of the licensing agreement and work with Epic Games to ensure that they are following best practices for handling proprietary information.
Also, if you are developing for any of those platforms you will need to get the required files from those developers. They are as far as I know, not fully implemented in the engine itself.