Auto-walk appears to fail to update the player's movement speed when they are crammed into a one-block tall space through swimming, piston crushing, etc. This is demonstrated in the attached mp4 files;

In the former, I am using a mod to keep the player in a crouching position with no ceiling. At 0:03, auto-walk is activated, and the player's movement speed is considerably faster while it is active.

In the latter, I enable auto-walk and allow the player to be crushed into a one-block tall hole with a piston. The player's speed does not change after they are compressed, which is not the case with standard movement.

While testing, it was found that auto-walk will accurately account for player actions such as eating and effects that are currently present on the player.