Google Chrome 83 began to disallow iframes from downloading unless the allow-downloads key is added to an iframe’s sandbox attributes: https://www.chromestatus.com/feature/5706745674465280
As some Power-Ups would like to be able to trigger downloads upon user action, we have added the
allow-downloads to the list of attributes.
With this change, the attributes currently included are:
allow-scripts allow-forms allow-popups allow-same-origin allow-popups-to-escape-sandbox allow-modals allow-presentation allow-storage-access-by-user-activation