From the translator via r/manga:
“Both 16 and 17 were the only ones altered to any significant degree so far (earlier chapters had some of the faces updated for consistency's sake), and both 16 and 17 were originally chapters that had been posted on twitter in chunks before being published. I would assume the author saw this as a chance to turn them into more "legitimate" chapters. 18 wasn't change any, and I'm not assuming the coming chapters will be changed much, either.
Maybe it would've helped if I'd added another page to the chapter to explain all that...“