How can I fix 'Missing product data' error in Google Content API feed?

The only way to resolve suspension issues is by checking all policies and ensuring you comply. Google will not give you specifics.

Here is my list: https://community.shopify.com/c/Ecommerce-Marketing/Checklist-Suspended-Google-Merchant-Center-Account-Fix-amp/m-p/1086444/highlight/true#M39128

And I recommend reading:

https://support.google.com/merchants/answer/6363310/follow-the-merchant-center-guidelines
https://support.google.com/merchants/answer/7052112
https://support.google.com/merchants/answer/4752265