Reset state to initial with redux-toolkit

Something like this:

const intialState = {
  returned: []
}

const showOnReviewSlice = createSlice({
    name: 'showOnReview',
    initialState,
    reducers: {
        reset: () => initialState
    }
});

This worked for me (mid-late 2020). Formatted with your code context as an example.

const initialState = {
  returned: [],
};

const showOnReviewSlice = createSlice({
  name: 'showOnReview',
  initialState,
  reducers: {
    reset: () => initialState,
  },
});