It appears that the "Publish to the Web" feature for Sheets no longer allows downloading of a sheet by URL, unless the "Share" feature is set to share to "Anyone with the link".
Up until yesterday, 11/18/2020, this extra step of making sure the "Share" setting was in place was not necessary.
Can you please confirm if this is a bug or a new and expected change? Thanks! ^_^
If a spreadsheet is Published to the web, it won't be accessible in any of the file formats (.csv, .pdf, .ods, etc.) to users who don't have access to the spreadsheet itself: for these users, it will only be accessible as a Web page.
This is not intended behaviour, since files that have been published to the web should be accessible to anyone with the link, no matter the sharing settings the spreadsheet itself has.
This behaviour has been reported in Issue Tracker several times: see this issue, this one and also the one you mentioned.
Specifically, the following issue seems to have been getting more traction, and it has already been reported internally by Google (see comment #3):
Therefore, I'd suggest anyone affected by this issue to click the star on the top-left in order to be notified of updates and to help prioritizing this.
Share the spreadsheet itself with Anyone with the link as Viewer role.
