Can I restrict structures to spawn on a certain block in 2024.1?

I have a "structure" that spawns in a custom biome, everytime it spawns on land everything is okay, but it also spawns above water, which is not what I want. I tried changing "Type of reference ground detection" to "motion blocking", because in the official guide it says "supports fluids such as water", but it spawns above water anyways. I tried searching up how to remove water from biome, there is no way. Can someone please help me?