I don\'t know what I did but I don\'t know how to get rid of those arrows on the left.
If the Toggle Visual Space
icon shall be added to a Visual Studio toolbar of your choice, because it shall be turned on and off via mouse click, then follow this instruction:
Customize the desired toolbar
Click on Customize...
Click on Add Command...
Go to Edit
and chose Toggle Visual Space
Click on OK
Tested with Visual Studio 2019.