Crawling under/in hopper

In survival it is possible crawl under/in a hopper as in the 1x1 space where the hopper is placed

What I expected to happen was:
I expected it to act as if was a chest (for example as a non full block)

What actually happened was:

I crawled into the 1x1 space

Steps to Reproduce:
1. Go towards hopper with at least two non full blocks on top
2. Sneak and jump
3. Hold w the whole time

4. after landing spam the jump button and now you're crwaling under/in the hopper