As somebody who doesn't naively speak Latin American Spanish but was exposed to it a lot growing up, the "th" sound for some words with "c" (like "gracias") in Castilian Spanish really disturbs me. It sounds like everybody has a lisp.

About two years ago for me as well, they might have rolled it out shortly after you tried or maybe I was part of some A/B testing or something. But the setting seems to be saved because I’m never given exercises with vosotros in them.

¡Gracias! Vivo en California, así que hay mucha gente para practicar hablando conmigo, pero estoy tímido y practico solo con Duolingo por ahora.

Not our fault the posh snobs wanted to sound different and the commoners copied them.

Wow you're so smart. /s