Support charges are being passed down to a channel customer with standalone or consolidated billing blocks.
Partner Generated Billing (PGB) removes support charges on top-level 'consolidated' accounts for standalone or consolidated billing block configuration.
AWS has allowed support subscriptions to be placed within linked accounts so PGB will pass support charges on those linked accounts through to the channel tenant. This is expected behavior.
If you do not want the support charges to go through to the customer's tenant, a Custom Price Book will need to be configured to remove these charges.
You can read more about price books at the link below. Please speak with your Technical Account Manager regarding assistance with the configuration of a price book if needed.
https://apidocs.cloudhealthtech.com/#price-book_introduction-to-price-book-api