alt Hacker NewsOh! I recognize that font from the recent thread on fonts! It's called Maple Mono[0], and yeah the connected cursive italic lowercase l is weird. But it's also implemented/designed poorly[1], and there's a chance it only looks awful because of that (lol). But IDK because there's no example of it being done well to compare against. It certainly would look less weird if they just didn't try to connect them to preceding letters. Anyway, someone was gushing about it, and that struck me as very odd specifically because of how bad the lowercase italic l is, but you can disable that feature if you want. So maybe that's the version they were using.
The cursive l I actually like. We learn to write that here at elementary school (at around the age of six). So if quoting, a handwritten font is nice. I use such in my nvim config as well. But AFAIK such a font is proprietary. Now, this fella's repo owner is CN, so I doubt they learned such at elementary school. It is also, like you said, weird since it stands out. If the rest also used cursive handwriting letters it would've been fine. So yeah, classic case of cha bu duo, or a quick personal hack you'd be embarrassed to share).