$file->url() returning the URL to the physical file is deprecated, use $file->createFileUrl() instead.

File::url() currently returns the URL to the physical file, this was done to be able to return the URL to the file as the self-URL in hal+json REST requests.

EntityInterface::url() has been deprecated in favor of EntityInterface::toUrl() and this behavior was never ported to the new method as it does not correspond to a route. It is now officially deprecated in favor of a new method that allows to access the created file URL.

The new method also converts to a relative URL by default, this behavior can be disabled:

$file->createFileUrl() == file_url_transform_relative(file_create_url($file->getFileUri()));

file_create_url($file->getFileUri()) == $file->createFileUrl(FALSE);