In 2 different experimental worlds of mine, I have found that all waterlogged blocks on certain x coordinates will display their base texture on the top of the water they are in. This can happen both artificially, and by being naturally generated. However, usually you need to put at least 1 fence touching the block, and I believe this only works on surface level water. I have experimented with fences, gates, seagrass, and trapdoors, all of which exhibit this behavior.