Google has made changes to how your feeds work in Merchant Center for countries, removing the need to list a primary country and additional countries, and replacing them with target countries.
Google wrote it is removing the concept of one target country being the primary country for a feed. Google explained that the "primary country of sale" and "additional countries" field names will go away. Any countries that were designated as a "primary country of sale" or "additional countries" will be moved to a new field called "target countries."
Previously, Google Merchant Center feeds have had an associated "primary country of sale," and "additional countries" could be added as well. The "primary country of sale" was the first country selected when creating a feed - this is where the feed would be primarily formatted for and directed to. Then the "additional countries" were added after feed creation - places where the feed could also be targeted.
While this changes how countries for a feed are organized, "it does not change the actual countries targeted by any existing feed and requires no change to existing feeds or campaigns," Google said.
New Feed Label
Google also added an optional new Google Merchant Center feed setting field named "feed label." If you are using Google Shopping ads, feed labels will allow you to create a feed with a feed label of your choice (up to 20 characters long) which can be used to group offers that are intended to be targeted via an active Google Ads campaign.
Feed labels will allow more flexibility in campaign targeting; for example, feeds using the same language could be given the same feed label, making it easier to target those feeds in one Shopping campaign.
For merchants previously targeting their campaigns using the "primary country of sale", feed labels will allow you to specify a 2 letter country-code giving you the ability to target countries in a similar way to what exists today.
Forum discussion at Twitter.