The bug is that I'm unable to play split screen on the console bedrock edition.
Yes, I have a Nintendo Switch Online subscription.

So when I try to join with a second controller and account. I get the message I need Nintendo Switch Online in order to do that. Arlight.

But I get the same error message when I connect a second controller and skip the account.

The other thing I could do was disable multiplayer in the gamesettings. Didn't work.

So I looked up a workaround (this bug is here since 1.6.1), even that did not work for me.

Please Mojang, fix this. It's nice to have split screen, now make it work so we can play split screen.