I can provide additional information on how to resolve the error between QuickBooks Self-Employed (QBSE) and Amazon, @Us.r58441
We recently had an issue with the connection between QuickBooks Self-Employed (QBSE) and Amazon. However, this was already marked as closed and resolved. Since you're still having an error I suggest reaching out to our Customer Support for QBSE.
Their tools can isolate the issue you're having and help you resolve the error you're having by refreshing the connection between Amazon and QBSE. Here's how to reach them:
Let me know if there's anything that I ca help with your account. Take care and have a wonderful day!