Was there some changes done in GraphQL schema generations recently?

We have an application hosted in Atlas and Realm. We use the graphql endpoint to consume the data. Strangely our production instance had an issue this morning India time.

We have a schema defined like this in Realm

"userGroups": {
      "bsonType": "array",
      "items": {
        "bsonType": "string"

the equivalent GraphQL generated is now,

  userGroups: [String!]

We believe the ! wasn’t present in the past. Today morning out of nowhere our production app had issues executing GraphQL queries.

We had to change our code to use String! instead of String to fix the issue.

I’m trying to do a RCA here, and looking for some help.

Thanks in advance