I finally managed to collect 10 bananas(about 3-5 hours before the black magic dragon event came to an end) and I didn't got the dragon.
I saw some videos on YouTube that shows players that getting the dragon right away after they done collecting 10 bananas.
If needed, I can give proof that I have 10 bananas on my island.

@שקד-עובדיה close your game. When you restart, you should get it