If there's even a name for it?
I saw this question that explains why but I'd love to know if there's a name for it. The linked question mentions superdeformed but I figured there's a Japanese name, if there's anything.
They do it in many anime (and manga) and it's used with the character is embarrassed, sometimes it's when they're tired, annoyed, or confused.
It reminds me of chibi but it's even simpler than that and doesn't really make them look like kid-versions.
From Fullmetal Alchemist: Brotherhood: