Problem type
Role slug taken
role-slug-conflict
What it means
Creating a role whose slug is already taken in the same scope, or blocked by a role in the other scope; or, when promoting a sandbox, an app-scoped role whose slug a workspace-scoped role on production already uses (errors[] names each one; nothing is promoted).
What to do
Choose another slug. When promoting, delete or replace the conflicting workspace role on production (a role's slug cannot be renamed), then promote again.