Do you support the Amazon PAAPI (Product Advertising API) v5.0?
In January/February 2020 Amazon sent an email to announce that they are soon upgrading their API to version 5.
Fresh Store is fully updated to use this version (since October 2019) and there is nothing you need to do.
The Amazon API is also known as the PAAPI (Product Advertising API).
If you have any questions, please drop a message to support.