Issue is that artist only uses three colours: black, white and same tone of grey. Also lack of details don't help. Artist also rarely uses lines to separate but uses contrast between white and black instead. It is difficult to recognize what's going on in one panel.
Edit: use last panel with the wizard's face as example. Lacks details, no lines to acentuate border of face (look at cheek and chin), lack of degradations make it look flat no volume, barely any lines to define hair (this would be normally acceptable but with this style it only makes it worse). So in the end it looks like blobs of black, white and grey. It is hard for eyes or brain to immediately recognize a pattern/face.