CodeSandbox iframe denied

This page reproduces codesandbox-client issue 8881. The iframe below should load a CodeSandbox define embed for an index.html file containing only hello, but Chrome shows codesandbox.io refused to connect.

Open DevTools to verify the failing request. The expected regression signals are a 403 response and X-Frame-Options: sameorigin.

Embedded URL: https://codesandbox.io/api/v1/sandboxes/define?embed=1&parameters=N4IgZglgNgpgziAXKCA7AJjAHgOgBYAuAtlEqAMYD2qBMNSIeMUUlAOqiADQgRwBCaAIYAnAJ5IwQqHBgBfBUA

Expected: interactive sandbox

Actual: refused iframe connection