how to return a list of dictionary in graphene?

I am new on graphql and working with some datasets that is returned as a list of dictionaries.

snippet code:

class Player(ObjectType):
    username = String()
    role = String()

class Game(ObjectType):
    players = List(Player)

I'm wondering why below code doesn't work?

class Query(ObjectType):
        game_info = Field(Game, username=String(), role=String())
        
        def resolve_game_info(self, info):
            results =  [{
                        "username":"Malphite",
                        "role":"tank"
                        },
                        {
                        "username":"Teemo",
                        "role":"support"
                      }]
            output = []
            for res in results:
                 output.append(
                    Player(
                      username=res['username'],
                      role=res['role']
                    )
                  )

            return output

How I query in graphql:

query {
  game_info(username:"Teemo") {
    players {
      username
      role
    }
  }
}

Results to like this:

{
  "data": {
    "gameInfo": null
  }
}

Any help would this would be greatly appreciated!