The tables look like they have been created with https://excalidraw.com/ with "sloppyness" option set to high and pointy corners activated.

EDIT: Now confirmed by author https://news.ycombinator.com/item?id=37323895

I used excalidraw.com

It looks similar to the style you get from draw.io if you choose "Sketch" as the style for an object (add box -> "Style" from right sidebar -> Sketch).

Looks like they are hand drawn