You can only set a transient payload when you update a flow (such as during registration, login, or settings), not when you get or fetch a flow. The transient payload is designed to be included in the request body when submitting or updating a flow, and it is then passed along to any configured webhooks. It is not persisted by Ory and is not part of the data returned when you fetch a flow. For example, when updating a registration flow, you can include a transient_payload field in your request body:

json {   "method": "password",   "password": "super secure password",   "traits": {     "email": "<mailto:mymail@example.com|mymail@example.com>"   },   "transient_payload": {     "consents": [       {         "id": "cookies",         "given": true,         "date": "2023-03-02"       }     ]   } }

This payload will be available to webhooks but will not be returned or settable when you fetch (GET) a flow; it is only used during the update (POST/PATCH) operation of the flow [Possibility to define complex data types in the metadata of identity](https://github.com/ory/network/issues/187) | [Ory API Reference – updateRegistrationFlow](https://www.ory.sh/docs/reference/api).