Kibana setting timepicker:timeDefaults via API is failing in 7.12

Elastic Stack Kibana
1

The following request reports bad request on upgrading to 7.12

api/kibana/settings/timepicker:timeDefaults
{

"value": {
    "from": "now-24h",
    "to": "now",
    "mode": "quick"
}

}

Error:
{
"statusCode": 400,
"error": "Bad Request",
"message": "[validation [timepicker:timeDefaults].mode]: definition for this key is missing"
}

2

Can some one please suggest if any documentation exists for the new changes in this API.
Setting it via front end is also giving the same error.

3

Remove the "mode" from the json doc. this not a valid config any more.