How do win streak bonuses work in Hearthstone?
Solution 1:
Do win streaks stop at a certain level?
Yes, you no longer get win streak bonuses at ranks 5 and higher.
Are there different requirements at different ranks for win streaks?
No, it's always three wins at all ranks where win streaks exist.
Solution 2:
There are no bonus stars at rank 5 and above. Otherwise you could reach legendary rank with a win rate lower than 50%.