Oplog tailing with MongoDB Atlas

My app works fine if I only define MONGO_URL to be
‘mongodb+srv://username:password@cluster0.tqq7g.mongodb.net’.
But “mup deploy” fails if I also define MONGO_OPLOG_URL to be
‘mongodb+srv://username:password@cluster0.tqq7g.mongodb.net/local?authSource=test&w=majority’.
Do you see anything wrong in that value?