Yes, it is fixed now.
I would agree with that. It should at least stop you from teleporting to a Y position equal to infinity.
I would say that it is more related to MC-55419 than a duplicate of it, as the other bug is focusing on player coordinates and sky effects rather than player rotation.
@Galaxy_2Alex, shouldn't you only need to assign 2 GB of ram? http://minecraft.gamepedia.com/14w30a#Changes
It seems that the behaviour was reverted in 1.16-pre3, so this ticket should be reopened.