The ender dragon fight has a "safe spot" exploit when he shoots his acid

There is a safe spot near his bedrock nest when he spits his ender acid.

Watch this video at 7:40 and at 8:10
That safe spot makes the whole fight a joke. this is a serious problem that should be fixed.

https://www.youtube.com/watch?v=Wqb2Sn0F69I