Postgresql :Syntax issue in MERGE with JSON param in stored function - sql

Question

Facing syntax issue when I have json input, which needs to be insert/update values from JSON into the table which is a view
Expected
When Primary id matched with Item_id (PK) - update its corresponding values
When Primary id not matched with Item_id (PK) - insert into the view
Sample SP
drop function if exists sp_post_itemsx;
CREATE FUNCTION sp_post_itemsx(i_data jsonb)
RETURNS VOID
AS $function$
BEGIN
MERGE INTO vw_item_status_detail
USING
(SELECT
i_data->>'fulfillerId' fulfillerId,
t->>'itemId' itemId,
i_data->>'orderId' orderId,
1000,
t->>'skuCode' skuCode,
t->>'decorationTechnology' decorationTechnology,
(t->>'quantity')::numeric quantity ,
NOW()
FROM jsonb_array_elements(i_data -> 'items')) as t ON item_id = t.itemId
WHEN MATCHED THEN UPDATE SET
vw.quantity = t.quantity
WHEN NOT MATCHED THEN
INSERT INTO vw_item_status_detail(
fulfiller_id,
item_id,
order_id,
status_id,
sku_code,
decoration_technology,
quantity,
item_updated_time)
SELECT
i_data->>'fulfillerId' fulfillerId,
t->>'itemId' itemId,
i_data->>'orderId' orderId,
1000,
t->>'skuCode' skuCode,
t->>'decorationTechnology' decorationTechnology,
(t->>'quantity')::numeric quantity ,
NOW()
FROM jsonb_array_elements(i_data -> 'items') t ;
END;
$function$
LANGUAGE plpgsql;
ERROR: "vw_item_status_detail" is not a known variable
Not sure what is wrong with the syntax or MERGE doesn't work with insert for views table