It is about compatibility with Polylang. In GB Pro, If I choose in a query a post category in one language, it works in all languages. The goal of the feature request is to make it possilbe to define a page in a query in one language and to make it work in the other languages as well. This would be very useful to standardize blocks and make them reusable in multiples. Using dynamic data, this is not possible actually and it is necessary to refer to every single page in every language.
In WPSP it works like this: if I define a Page ID in one language, it works in all languages.