I think this is a great idea! I’m all for blurring the text of one’s native/fluent language more! It helps users focus more on what they remember and hear/see in their target language.
Can you move this thread to the Request category, so it’s more likely to be seen/considered/updated by the Team?
Moving A Thread From One Category to New Forum Category Details
I think it is more likely to be a bug than a request since it is blurred in the Practice option. I think the team just forgot to apply the blur in the quiz option.