Google Sheets API v4 append request receives HTTP 401 response for public feeds using API Key

Question

This is extremely similar to another question answered here about how to GET spreadsheet data, but I\'m trying to append data to a spreadsheet. Here\'s my s

Answer 1

Requests that write to the spreadsheet require authentication credentials. Even if the spreadsheet is shared publicly, when writing through the API the write must be attributed to a user.