Searchable, skimmable text from voice traffic — without anyone but the intended recipients ever being able to read it.
Server-side transcription requires the server to hold your audio in the clear. That is a reasonable trade for some products; it is the opposite of what this one is for. So the sender transcribes, and the text is encrypted into the message alongside the audio.
A transcript makes voice usable in the situations where audio is not: a loud yard, a quiet ward, a meeting, or a backlog of forty messages you need to triage rather than hear.
Feeding recorded audio to Android's on-device recogniser requires Android 13 or newer. Below that, the sending device cannot produce a transcript.
Server-side transcription is available as an org setting for teams that want broader coverage — but it drops end-to-end encryption for affected channels, so it requires an explicit acknowledgement and is labelled in-app for everyone in the conversation.