In Portuguese, too. And most other languages from Iberia*. And “x” is typically so rare in other orthographies that, for Portuguese speakers, rendering “x” as /ʃ/ (the “sh” sound) is almost automatic, so the first time that I saw “Xitter” I couldn’t stop laughing.

*with one exception: modern Spanish. And by “modern” I mean past the 17th century, because before that it was /ʃ/ in Spanish too. That’s where the Maya languages got that spelling convention from.

(Sorry for the off-topic.)