For the updateUser mutation, the id input field's description says "The ID of the user". That is misleading though – WPGraphQL users will think that they should pass in the WP user ID, rather than the globally unique identifier for the user object. Screenshot: https://cloudup.com/crBNDmBdh5z

I think that to avoid that confusion for the updateUser mutation and any other operations, it would be good to do a quick sweep through the plugin and make sure that any id input fields have their descriptions updated with text like this, for clarity & consistency:
The globally unique identifier for the <whatever type> object.

Who's with me? 🍺