It has not been moved. Some users on MacOS are seeing this but most are not, and I don't think anyone yet knows why.
I would suggest:
Removing OBS completely and reinstalling, backing up any profiles and scene collections as required;
Use the Reset UI menu item to reset OBS to its default UI if you have made any changes
Create a 2nd user account on the machine and run OBS to see if that user also experiences the same issue
Just worked out a work around. What has happened is when you resize the window between the preview work space above and the docks down the bottom (dock are the seen, source, mixer etc) The vertical bar appears when too low, brings up the scroll on the right of the sources dock. When I raised that up to make the main preview window smaller the scroll covering the lock icons disappeared.I was afraid someone would say a reinstall. I will look into that and how I can back up things first. Thanks