Affected versions may also be earlier versions.
Problem 1: when a ghast fireball hits water the ball explodes immediately, just like when it would hit a solid block. The expected behavior would be that it travels through the water.
Note: The ghast is able to target the user through water, so this is correct behavior
Note: When I fireball travels through a water curtain (downward streaming water) in Java edition, the trajectory of the fireball is changed to a slightly downward direction. Is/Will this be implemented in Bedrock too?
Problem 2: when a ghast fireball hits horizontally placed trapdoors (including iron trapdoor) it just travels through the trapdoors without exploding. expected behavior: the fireball should explode upon hitting the hitbox of the trapdoor. Note: when the trapdoor is in vertical position (opened) the fireball shows normal behavior and explodes.
Reproduction info: bring a ghast to the overworld or use creative mode to spawn a ghast. Lock the ghast in a room and open up enough space for it to shoot fireballs. From there one can experiment with creating a water curtain and see what happens.
Also not sure whether this would be expected behavior or not: when a ghast fireball hits a wire (traphooks) the wire is not triggered, but destroyed and string is dropped.