This idea has been lurking around in the community for years already, but never has made it into an idea.
The idea to remove a data protection concept error in Smartsheet. As an editor you cannot see what's in hidden columns and you cannot make them visible. Makes sense because not everyone should see some content in a sheet.
BUT every editor can export to MS Excel and the resulting file contains all hidden columns made visible and also the data in the columns.
So Smartsheet make the data protection behaviour in sheets and in the export of sheets consistent!
Could be, that you use the same engine used for the Excel Backup, but that's not the same use case.