Code:
08:31:35.502: Loaded scenes:
08:31:35.502: - scene 'Scene':
08:31:35.502: - source: 'Display Capture' (monitor_capture)
08:31:35.502: - source: 'Browser 2' (browser_source)
...
This is "Browser 2" source you added to the sources list. By default, it points to test page of this site. OBS renders sources in layers, one above other. If you don't need the "Browser 2" source - simply select the source in the Sources pane and remove it with corresponding "Recycle Bin/Trash" tool button.