This is happening on 18w50a.
I would add that on 18w50a throwing a riptide trident at a mob (any level works) will 1 hit kill the mob.
I tried with pillagers and drowned (under water) they all die when you collide with them.
This is everywhere,, not only in the shattered savanna. I have prints from pretty much all biomes with lots of Tetris blocks floating in the sky. You guys can call a bug a feature if you are not willing to fix it...
Issue persists in 18w21a.
I do not get breathing bubbles while swimming in a column of flowing water. I only get the bubbles in the water-source block.
Still happening on 18w50a.