In eZ Publish you could place a single content type (content class) in multiple groups. Currently this is not possible via eZ Platform UI, but the schema still works and admin works as well.
However with a single type in multiple groups the GraphQL Schema generation fails:
Steps to repeat:
1. Import old eZ Publish database with a content class in multiple content class groups
2. Upgrade schema to eZ Platform v2.5.0
3. Run "./bin/console ezplatform:graphql:generate-schema"