In Vanilla, liquid-clipped behavior treats liquid surfaces as though they were solid targets for the sake of block placements; lily pads are notable users of this. For custom block placer items, the minecraft:liquid_clipped component is meant to imitate this behavior. Unfortunately, it is inconsistent with Vanilla in 2 different ways:

• If a solid surface is available behind the water layer, that surface will be treated as the target instead.

• Blocks that do use liquid surfaces targeting are placed inside the liquid instead of atop it.

Demonstration

The following video demonstrates the inconsistencies:

Take note of 3 things:

• The first lily placement is targeting the bottom center red position behind the liquid layer, but the lily pad is placed in a closer position.

• The generic placement (apple icon) is targeting the center liquid position; however, the stone block is placed behind as though the placer would not be liquid clipped at all.

• The custom lily pad placement item (snowball icon) can never place, as the lily pad’s placement filter (air atop water) always fails. This is because, like the generic placer, the lily pads are attempted to be placed in the water, not atop it.

Reproduction

This example is taken from the behavior pack in the following world attached for convenience:

This world can be opened (in Minecraft Preview) for inspection or unzipped to access the code associated with such.