Deprecations and removals in Chrome 83
Disallow downloads in Sandboxed iframes
Chrome now prevents downloads in sandboxed iframes, though this restriction can be lifted via an 'allow-downloads' keyword in the sandbox attribute list. This allows content providers to restrict malicious or abusive downloads. Downloads can bring security vulnerabilities to a system. Even though additional security checks are done in Chrome and the operating system, we feel blocking downloads in sandboxed iframes also fits the purpose of the sandbox.
Intent to Remove | Chrome Platform Status