Bluescape uses a customized UI for GraphQL playground, comparing to default UI and latest version of GraphQL playground it has some disadvantages and hard to work with
We are working to migrate to the Altair graphQL playground client: https://altairgraphql.dev/. This work should be completed soon, and I will announce when it is ready.
I hope this playground solves the issues you have been facing with the layout.
Regarding loading our schema in your own playground client, I’ll have to confirm with our engineering/security team regarding the CORS issue.