因为您在json_data中的“region”键提供了str数据而不是dict，这就是为什么您得到了错误的JSON值。请尝试将其设置为dict。
试试这个数据

json_data = {
  "id": "123",  
  "name": "Jack",  
  "createdAt": 20221212,  
  "region": {"country": "USA", "city": "NewYork"}
 }

您可以通过修改现有代码（其中的值为str）来实现这一点，因为在本例中，region\有引号""。因此，您可以使用内置的json模块来处理这一问题。

import json

def flatten_data(json_data):
    """
    Arguments:
        json_data (dict): json data
    Returns:
        dict : {a:1, b:2, b_c:1, b_d:2}
    """
    out = {}

    def flatten(x, name=''):
        if type(x) is dict:
            for a in x:
                flatten(x[a], name + a + '_')
        elif type(x) is list:
            out[name[:-1]] = x
        elif type(x) is str:
            try:
                y = json.loads(x)
                flatten(y, name)
            except:
                out[name[:-1]] = x
        else:
            out[name[:-1]] = x

    flatten(json_data)
    return out

json_data = {
  "id": "123",  
  "name": "Jack",  
  "createdAt": 20221212,  
  "region": '{"country": "USA", "city": "NewYork"}'
}

print(flatten_data(json_data))

• • 输出：**

{
  "id": "123",  
  "name": "Jack",  
  "createdAt": 20221212,  
  "region_country": "USA",
  "region_city": 'NewYork'
}