In late November I was flying Emirates F to New York. I asked a flight attendant what the cabin crew knows about the passengers, eg, Skywards status, ticket details, upgrade and type of upgrade, and she said "Everything. Absolutely everything."
I don't know how other passengers would have known definitively that the OP was in an upgrade seat without the OP telling them, but my personal experience is I am frequently looked down upon by other F passengers simply because I don't look like one of them, so I'm inclined to sympathise with the OP there.