Hello.
Newbie here but, long time lurker.
I successfully airplayed an episode of Goosebumps and a random homepage featured show via the iphone Netflix App running B4 on XS. Both popped up in Safari pretty smoothly to the website on my MacBook Pro 2018 running 12.0 B4.
To invoke it, on the Netflix iOS app, I selected a show, tapped hare, tapped more options and finally, tapped air drop. (had to do that once. for the second show I tapped my MacBook.)