I have an iframe with src attr set to https://example.com/path. This URL redirects 301 to https://othersite.com/path. This page loads some JS and creates a BroadcastChannel with a listener on it. It then opens a new window to https://othersite.com/path2. This page load some JS that creates a BroadcastChannel with the same name and does a postMessage. The problem: it never arrives in the iframe. The weird thing is, it does work if the src of the iframe is not a redirect. But that doesn’t make sense because even though it is redirected, the origin is determined by the page that is eventually loaded. So the origins are the same (yes I checked that), and the BroadcastChannel names are the same. So why doesn’t this work??