Run this command:

/attribute @s minecraft:generic.step_height base set 2.0

Despite this being a gap the player can fit through, it's impossible to walk through it (unless you aren't touching the ground). Walking straight will step you onto the top carpet, not the bottom carpet.

This applies for distances up to 9 blocks relative to where I would expect to step up to.

Some effects of this are very unexpected. For example, with very high step heights, walking up this hill will randomly step you to the top of this tree (where the sign indicates) rather than up the grass block. This is how I stumbled upon this bug, and I didn't even notice the tree there while I was walking up the hill, so I was very confused when I was sent to the top of it.