Even small changes, like tweaking a product title or swapping an image, can cause your ROAS to dip for a few days. It’s frustrating because it feels like you're just improving the feed, but Google sees it as a whole new learning cycle.
Here’s why: every time you update something like a title or description, Google reassesses how that product performs in auctions. It might show up for slightly different search terms, get lower click-through rates, or confuse the algorithm’s past performance data, so the system has to “re-learn” what works.
What helps?
Try batching your feed updates instead of doing them daily or randomly. Maybe update once a week so the system isn’t constantly resetting.
If you’ve got products that are doing really well, try not to touch them unless you really need to. Even a minor title change can throw them off.
Consider using supplemental feeds in Google Merchant Center. That way, you can update some info (like labels or sale messages) without messing with the main feed.
And if you do need to push updates, do it early in the week when traffic is lighter, so things can stabilize before your peak days.
Bottom line: the feed is basically your ad creative in Shopping campaigns. Treat it like your best-performing headline; you don’t change it unless you’ve got a really good reason.