I was listening to The Third and uppon listening to 13, it seemed to me the drawings were awkward, making the characters look fat. So, I did a comparison with past and future episodes, and to my delight, it’s the only episode that’s this way.
The change is stunning. It really is another artist.
Let’s take a look.

The second image is the original of course; I’ll keep it this way from now on. But, hey, if that isn’t obvious. Just look at the nose!

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Although closer to the original, it’s far from it. The nose, the face’s roundness, the hair detail. Everything!

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Honoka and Millie. This one’s most notable aspect is probably the lack of hair detail on Millie.

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And for the final, fat face!

Really, I hope the artist of the filler never makes Anime or Manga. May you stay as a good in-between-animation frame artist.