Summary:

When a piston pushes a block which a player is standing on, the player is left behind by 0.5 block lengths.

Step to reproduce:

1. Place piston or sticky-piston horizontally.
2. Place any blocks horizontally so that it can be pushed by the piston.
3. Get on top of the blocks. (except honey block)
4. Activate the piston.

Observed result:

Player moves 0.5 block toward pushed direction.

Expected result:

Player moves 1.0 block toward pushed direction.

Notes:

Other entities follows the standing block accurately.
At least 1.17.11, player followed the standing block accurately.

Affected entities:

Player, Boat (that player is riding), Horse (that player is riding and saddle is equipped)

Platforms:

I confirmed this bug occurs in Win10 and Android at least.

Versions:

This bug started to occur between release versions 1.17.11 and 1.17.30.