I was extremely surprised by this answer:
Is Netflix streaming really illegal on discord
Strictly speaking, it's illegal, yes. Netflix in particular is relatively good at preventing screen recordings or similar forms of illegal streaming.
If you do something like this on a server that is publicly available, that's even more problematic. If the whole thing is reported to Discord, a ban would be very likely.
There are also discord servers and they say is legal
As I said, it is not. And of course they say that ;-)
Can't I watch the broadcast together with a friend (only friend)?
No
I would say that in this case it's more of a gray area if you only do it with your friends.
In general, however, the distribution of copyright-protected material without explicit permission is prohibited and of course series and films on Netflix are included.