What Rules dictate the sort order of __name__ in an index?

[glumb]

I read in https://firebase.google.com/docs/firestore/query-data/index-overview that

By default, the name field is sorted in the same direction of the last sorted field in the index definition.

However if I create this query:

const query = await db.collection("Auditlog")
  .where("tenantID", "in", ["IeZfE0yKWs0kGBl1IG5M"])
  .orderBy("_meta.dateCreated", "desc")
  .limit(50)
  .get();

firebase gives me a link to create this index

Where __name__is not sorted according to the last field in the index, which would be _meta.dateCreated:DESCENDING but sorted ASCENDING for unknown reason.

Why is this? By what rules is this sorting determined? We need to create the indexes programatically and therefore need to know what index is required.