This was just forward of and below the windshield washer fluid reservoir.
Depending on vehicle options, or lack of, there’s rubber body plugs that fill those holes.
Here’s a picture of the area from when I was working on my yellow 68 XR-7.
There’s no option that affects that hole. It’s a tooling hole used to locate the part. It is supposed to have a rubber plug on installation. Perhaps they were out of rubber plugs and used that piece of gaffer tape instead.