I think it's a combination of the last chapter being what he consideres to be a volume end point, trying to arrange an actual physical release for this series, and feeling like he needs to work on his manga style art. For the past few months he's been working on updates for his older webcomic TRIGGER in a manga style, but AFAIK he hasn't posted any.
From what I've seen and heard, artist is going through some health issues, so let him get some rest y'all. 2 months is pretty much nothing, some mangas got absolutely no news after 2 years. You're lucky he still posts some sub-chapters.