Render.yaml schema's `additionalProperties: false` prevents DRY

Trying do something as simple as

repo: &repo "https://bitbucket.org/someorg/somerepo"

in render.yaml results in an error at Blueprint Instance creation time, specifically with field repo not found in type file.Spec. I would assume this is because of "additionalProperties": false found in https://render.com/schema/render.yaml.json.

I find this extremely limiting to be honest: how is one supposed to manage anything more complex than a couple of resources like this? Ok sure, I can (I guess, haven’t tried) define anchors on fields defined within services, but this means promoting one of the services as the “common definitions source of truth”, which feels very wrong.