To view a version note, select the notes icon next to the version number. The note displays in a modal below the selected icon:

Authors with custom roles that don't have permission to edit article versions can view version notes, but they cannot add, edit, or remove them:
Sample Version notes when author doesn't have permission to edit versions. Note they can only Close the note.The icons for these authors will show dark grey instead of yellow:
Sample Versions section for author who doesn't have permission to edit versions