WPGraphQL – How to fetch data based on a Where attribute?

I have created a post type called LearnArticles in wordpress and another post type Learn Categories. Now I have linked both of them and I can access the Learn Categories data under the Learn Articles. But when I am trying to fetch data of a particular category I am unable to find the Learn Categories field in the Where attribute of the Learn Articles.

But on the default post category, there is an option to filter using the category ID.

How can I get my custom category type (Learn Category) in the Where attribute?