Summary:
A player cannot jump while crawling, unless they are near an incomplete block (even without a collision). If the crawler is in the same block/nearby to blocks such as rails, buttons, carpets, iron bars, etc. he can jump.

Steps to reproduce:

1. Crawl in a space 1 block high.
2. Try to jump.
3. Place a button underneath.
4. Try to jump.

Observed results:
You cannot jump while crawling except in certain scenarios.

Expected results:
You can jump while crawling.

Video:
Minecraft Preview 2023-03-10 15-02-28.mp4