No. Your audio and transcripts are never uploaded to our servers.
You can choose to store your recordings in iCloud Drive or locally on your device. The transcribed text is also stored inside these audio files.
We use Apple's Speech-to-Text framework to perform the transcription. Typically the conversion of audio into text occurs on your iOS device, however, depending on the device capabilities and the language being transcribed, the audio may be uploaded to Apple’s iCloud servers for processing.