As of 2024-05-14 a change has been implemented to enforce access token expiry. If you see higher numbers of HTTP 401 responses, please check tokens that may have expired. For more details, including how to mitigate disruption, please check our docs guide on Expired Access Tokens. If you have a support contract, you may open a support ticket for additional assistance.
Credit to Bas1c for finding that Address-received GetChain (used for handler_swap.go GetFee) cannot distinguish between ETHChain and AVAXChain,
as well as for the suggestion of using TargetAsset to determine chain instead.