Looks like something one could make pretty easily with Excalidraw (https://excalidraw.com/) although the font seems slightly different.

Maybe not the case, but often that style was made using Excalidraw: https://excalidraw.com. Playing around in it, the font at least appears the same.

Haha, I had the same thought about the program and the opposite conclusion about the font! Many characters like g and p look similar, but the lower case t has a curl on the bottom in Excalidraw, and is straight in the article's diagram.

Edit: on second look, it is the same t. I saw some images in a search for Excalidraw with a different t, but when I tried the actual site it was the same. Sorry for the noise!

I'll reply here (because I simultaneously replied to your other comment but removed it). I also thought it was funny we had come to opposite conclusions based on the same data.

Type out "Bottom-up" in excalidraw, it matches perfectly. The lower case `t` has a curl on the bottom in the diagram too.

EDIT: Re Edit:

No worries about noise. I had a good chuckle with our near simultaneous replies which was nice after the way our project has been going this year.