Flooded stairs in igloo

I was exploring my world and then i found an igloo then i entered and the stairs were flooded of water, there was a flooded cave next to it.

 

How to reproduce:

 

• 1.Create a world with this seed: 6456867176503131171.

• 2.Tp to these coordinates: -449 63 229.

• 3.Now look how the stairs are flooded.