This only happens rarely and is difficult to repeat.

I built a vertical shaft to access an underground area.  Most of the shaft is just air, but three blocks above the ground there is one water source block.  By normal falling rules, the player's fall distance should be reset when passing through that water block and the player should land as if they only fell 2 blocks and not 53 blocks.  However, twice the game has glitched while the player was falling and the player died when hitting the bottom.

I had a similar shaft in versions 1.14.x and 1.15.x and this never happened to them.  It has happened twice in pre-1.16 snapshots, including once in 20w21a.

To duplicate:

Create a vertical space at least 30 blocks high.

Put a sign on the second block from the bottom.

Put water in the block above the sign.

Walk off from the top to the bottom.  Normally you will land safely, but occasionally you will die at the bottom.

(I think that this happens because the game happens to glitch right as the player reaches the water block, and the game doesn't register that the player passes through the block on the way down.)