I was cabin crew for 20 years with a legacy airline in the states. I know the ins and outs of crew behavior and non-reving. Including my child non-reving first class international.
Something is not adding up.
No way are passengers in both outbound and inbound flights going to call out your actions unless it was really bad.
Talking to your kid isn’t going to illicit that. Those passengers are in their own world and encapsulated lie flat seats watching movies, doing work on their laptop, or sleeping. Unless you were obnoxiously loud or outright ignoring paying passengers, they really don’t care.
Crew suggested he take off his mask? Ok, this is where I think we’re being punked. No way. This just isn’t legit. Right now masks are like seatbelts, a requirement. As OP said, he wore it so that can’t be the reason for the complaints.
Yes, as a non-rev you are supposed to be absolutely discreet as possible. This obviously didn’t happen, but it is not cause for all the complaints. First class passengers fly enough to know about employee perks. This isn’t a shock to them.
My initial thought was they were upset you’re traveling with him right now, during a pandemic. But as other posters pointed out, that is baseless because they’re traveling too. Sure maybe one or two may have thought that, but ten? Nope.
This just doesn’t add up. OP is leaving out a key piece, or trolling.