This issue is too frequent with the Quickbooks connection. Every other day the Quickbooks connection breaks and all synchronization packages throw 400 Bad Request Error. The Metadata Cache has been set to "Infinite" in the connection settings so that the Access Token does not refresh automatically.
When the connection is reset by signing in again in the Quickbooks account the sync runs again.
Is this is an issue with Quickbooks or Skyvia?
Last week there was a similar post with the same issue and in the comments, it was mentioned that the issue was with Quickbooks and the bug has been resolved. I am still facing the issue as the sync stopped working on 27th November. I had to re-establish the connection for the sync packages to work.