Once you have enabled recording at a meeting, it appears as a dashboard in the meeting, and as a red bar at the top of the screen. The red bar will also appear when you leave the app - for example if you open another app during the meeting.
If your mobile screen is locked, the red bar will still indicate that you are recording the meeting.
In addition to the red bar at the top and the dashboard, inside the meeting you can also see that the recording is enabled as the "Mute" and "End" buttons will be visible.
On the meeting overview, there is a red dot indicating that the meeting is being recorded.