Starting in August 2020, Google is changing how Showcase Shopping ads work.
In showcase shopping ads, costs are calculated as an engagement. Before an engagement would be when someone spends more than 10 seconds in the expanded ad section or when a product or link is clicked on. Instead, each click will be charged as an engagement. No longer will ad views of more than 10 seconds, accumulate cost.
Showcase Ads will no longer show header images. So adding or editing header images is no longer possible.
Impressions are now counted for each product you have in the carousel. Before an impression was for the whole ad unit, but now if you have 36 products in the carousel, you will get 36 impressions. This means your impression share will increase, and your CTR will drop.
Consumers can now view more product data, such as product titles, prices, and customer ratings.