I have been looking for this answer too because we are a Credit Union and need to lock down the Board Meeting recordings. I stumbled on instructions on creating a Team (or Channel) within Teams. (Under Chat is Teams).
Create a Private team and assign only those that need access to the recordings as Owners. From there do a Meet Now to start a quick meeting and then start a recording for 30-60 seconds. Stop the recording and end the meeting. Under your team name you will see General. On the right, near the top, click on Files. The Recordings folder will appear. Hover over, click the 3 dots and select Manage Access. Remove the view and edit permissions. Leaving only the owners to see and access this folder.
Create future meetings from this Team. When you record, they'll go to the Recordings folder. Others can see the recording in the chat, but access will be denied. People not members of the Team can be invited, but they will not see the chat/posts, even during the meeting.
Shout out to NWU - I found their instructions online and tested this. Enjoy!
