>>280089684
Yotsuba's dialogue contains kanji very rarely, because, you know, she's 5 years old. It reflects on her as a character.
You can try this yourself, but if you throw "あんしんでつ！" and "安心です！" into Google or DeepL you're going to get different translations. This isn't an isolated instance and these translating programs do that a lot.
The scanlator most likely didn't know the associated kanji for "あんしん” and just went with what was spit out at face value.
