If I upload a file to firebase storage with a custom data
const someCustomMetadata = { customMetadata: {'x': 'xxx',} };
updateMetadata(someRef, someCustomMetadata)
and then some user downloads this file by calling a firebase function which returns
const [url] = await bucket.file("myFile").getSignedUrl(urlOptions)
will that user be able to extract someCustomMetadata from the file?
When a user download a file via a signed URL he/she cannot extract the metadata attached to the file.
For that you would need to call the getMetadata() method.