We recently restored a site collection using Restore-SPSite. Following the restore, a new page appeared that prompted me to select the authentication provider. There is 2 choices in the dropdown and both are "Windows Authentication" (see first image below).
This happens for ANY site collection, even those I did not restore. The message of the prompt page is "Select the credentials you want to use to logon to this SharePoint site:".
There was a duplication of the authentication providers (2 providers for the same zone), which I deleted. Unfortunately, it did not resolve the issue. I'm really confused, I have no idea what may have caused this to happen. It does not make any sense to me that the command Restore-SPSite could change a configuration at the farm level.
Any help would be greatly appreciated.