My hitbox is becomes smaller

My hitbox becomes smaller when I do the following:

Instructions

1. Press F3 + B to open the hitbox view.

2. Build a cobblestone generator.

3. Stand in front of the cobblestone.

4. Crouch and break the cobblestone.

5. Before the cobblestone regenerates, press W once and move forward a bit.

6. When the cobblestone regenerates, look at yourself with F5.
   Result: Your hitbox will shrink.
   Note: This also works in earlier versions like 1.21.9 and 1.21.8.