If I understand the latest updates from Google, they will discontinue the support for Global Endpoints for Google Content API.
When I look at their documentation I find this for .NET: https://www.nuget.org/packages/Google.Apis.ShoppingContent.v2_1/
Does anyone know if this is using the new endpoints?
The default endpoint is still https://www.googleapis.com/content/v2.1/, because that's what's currently in the Discovery Doc. Once the Discovery document has been updated, the next release (which is automated) will reflect the change.
If you need to use the current client library version but want to explicitly specify the base URI yourself, you can do so using BaseClientService.Initializer.BaseUri.