Configuration:

• user execute query in "DB_query"
• user authorization stored in "DB_auth" (user has no acces to that db)
• config:
  url: mongodb://user:password@host:port/DB_query
  options: {"authSource": "DB_auth"}

const client = await MongoClient.connect(url, options);
const result = await client.db().collection(collection).find(query, fields);

Expected: query executed in "DB_query"
Actual: query executed in "DB_auth"

This thing seems caused by this change i get error "MongoError: not authorized on DB_auth to execute command".
Db in url is differ than than authSource, after latest upgrade driver try to execute query in authSource instead of db specified in url.

Behavior exists in 3.x and 4.x mongodb, standalone and replica set