If you are reading this post, you more likely got a warning message as follow, when opening the mapping page from the Mapping Sheets add-on
The map data files are those .json files the Mapping Sheets add-on creates within the xsMapping folder in your Google Drive. The Mapping app reads that data file using an ajax call.
If that data file is not Public (shared with view access to anyone) you might have this issue in any of the following scenarios:
If you want to share your map with others, you have to share the xsMapping folder (or the specific json data file there) with those other users, or make it Public (anyone can view) if you want to be accessible by anyone.
How to know if I am logged in the Chrome browser with multiple Google accounts?
> Open a new tab in your Chrome browser and click in your picture or initial in the top-right area of the new tab content.
See a sample screenshot below showing multiple accounts active in the same browser session
Some instances on the Safari browser causing this warning
When the .json data file is not public, Safari might throw a "too many http redirects", when accessing the data file. We still don't know the root cause, but it looks like Safari does something different to the other browsers.
The solutions might be any of the following, as applicable: