I'm not sure whether it's a difference in scan quality or a change of technique by the author but the image looks a lot softer than in previous chapters. Not in a bad way mind you, it's just something that immediately stuck out for me (even though the last chapter was... 7 months ago?!).

Great chapter as usual, I love me some Yotsuba shenanigans.

It's been a while since I've seen/read Azumanga Daioh but the teacher was the same Osaka right?! I got super excited seeing her but in not sure it's meant to actually be the same person

I felt that way too. Then when Osaka showed up I wondered if it was intentional to call back to his simpler style back in Azumanga Daioh

That seems to be the general consensus among the comments I've seen about this chapter. Even if not intentional, this is the canon now.