Log in to your Google Merchant Center account.
Navigate to the account or subaccount containing your Google Shopping feed.
In the left-hand menu, click "Products", and make sure you're on the "All Products" tab at the top of the dashboard.
On the right side of the page, above your product list, click the Columns icon and select "Modify columns."
Select all available columns by checking each box, then click "Apply."
Once your table updates, click the Download icon above the product data table to export a copy of your Google Shopping Feed.
What if I see multiple feeds?
You can look at the "Products" column showing the product count, "Feed Name", or "Country of Sale" to get clues as to which feed belongs where.
What if I don't see a product feed?
Navigate to the "Products" menu on the left, and select "All Products". This will generate a list of all the active products in your Google Merchant Center, which you can then download by clicking the arrow in the top right-hand corner.
What if I'm using Google Sheets to submit products?
You can download this by navigating to the "Products" menu on the left, select "Feeds", and then "Open" the Google Sheets feed. From there, you will select File > Download > Comma-separated values (.csv).
See below for information from Google
"Downloaded product data will reflect raw data submitted to Google via your primary feed, in addition to any modifications from supplemental feeds, feed rules, and automatic item updates. This allows you to see your product data as Google uses it, and identify changes you can make to improve your data’s performance."