I don't think that's sharpie. It's very uniform. In some of the images, it's done per word for adjacent words—who would do that by hand, making all the intricate rounded corners? And in some, the censored areas overlap, and the overlapping area is transparent (like a Venn diagram), which suggests it was done digitally. I don't think it's physically possible to achieve that effect by hand, at least not without being extremely deliberate.

Which begs the question, if this was done digitally, did nobody look at the result? Nobody saw that the redacted text was easily still readable?

From the look of it, it's like they used a tool for highlighting, with the color set to something dark.

Without being too much of a conspiracy theorist, it almost seems like this was an intentional leak. Hanlon's razor and everything, but it wouldn't really be "malice" if they were trying to either sow false information or reveal details that they wanted to make seem like they were trying to keep private.