According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/403, re-authenticating should not fix this issue, but looks like it does in this case.
I wonder, does this error mean that the user did not accept the authorization scope for Content API in the Google login popup? In my testing of Google API Explorer, it looks like the users would get HTTP 401 instead under that circumstance. Can we get this HTTP 403 error for any other reason?
Please let me know why my users are seeing this issue and if there's anything that can be done to fix this. Is this a transient issue on Google's side, a user error, or something else? I am also happy to reply privately to give more information for debugging purposes.
I’m James from the Content API Team. Thank you for reaching out to us.
For our team to further investigate, can you please provide us with the following items below?
Kindly provide the requested items above via ‘Reply privately to author’ option, if the private option is not available on your end, then please send it over through this email <shopping-a...@google.com> instead.