In March Microsoft announced the availability of live transcription in Microsoft Teams meetings for English (US). This feature also supports speaker attribution. After the meeting is over, the saved meeting transcript will be available for reference and download in Teams for desktop and web.

Microsoft Teams Live Transcription

Previously the feature was only available for scheduled meetings, but on the Microsoft 365 roadmap, Microsoft announced the feature is now also available for unscheduled/ad hoc Teams Meetings, saying:

Microsoft Teams: Live Transcript in unscheduled Teams meetings

Now unscheduled/ad hoc Teams Meetings are supported by Live Transcript.

The feature is at present still only available for the Microsoft Teams desktop app, with the roadmap not mentioning support for the web yet.

via onMSFT