How to investigate the issue
Price differences can arise when a store updates a listing but not its feed, when a sale starts before the feed refreshes, when shipping or tax display rules differ, or when structured data uses an old currency or amount. Google expects product prices and currencies to be consistent between the feed, product landing page and checkout. Start by choosing one affected product and write down the feed id, price and currency. Next inspect the product page customers see, the Product/Offer JSON-LD and actual checkout price. If the country or currency has changed, confirm the correct localized URL and target country. Do not automatically overwrite a feed with the value from an unknown page; pricing rules and promotion dates can explain some differences. For sale_price, check that the regular price remains valid and the sale has a meaningful effective period. After correcting the trusted source, regenerate the feed and let the Merchant account refresh. Verify any remaining issues in Merchant Center itself; a local tool cannot view private diagnostics.
Relevant free diagnostic tools
Official reference
Google Merchant Center product data specification. Check current policies and your account for definitive eligibility details.