On the new Helix endpoint, https://dev.twitch.tv/docs/api/reference/#get-extension-transactions and therefor https://dev.twitch.tv/docs/api/webhooks-reference/#topic-extension-transaction-created the signed receipt that comes with onTransactionComplete from the JS Helper is missing. In order to audit and avoid man in the middle attacks, a signed JWT that can only be verified with the client secret should be sent on all endpoints sending monetary transaction data.