In case you need to migrate to V2, consider checking this documentation.
Furthermore, I’m not seeing a direct way showing the API version via the Dialogflow CX.
Here’s what you may do instead:
Monitor the Speech-To-Text API request. If you have access to API request logs through Google Cloud Audit Logs or Monitoring, look at the actual Speech-to-Text requests being made by Dialogflow CX.
File a feature request through the Google Cloud Platform issue tracker. Specifically request that Dialogflow CX explicitly indicate which Speech-to-Text API version is being used for a given model. While there’s no guarantee of immediate changes, this feedback can help improve the user experience and provide the transparency you need. Also, this provides valuable feedback to the product team. You may keep an eye on your submitted feature request to monitor the update.
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