Is it right to think that "Zazwyczaj" fits for negative sentences and "Zwykle" for others than that ??
No I tried checking dictionary for any difference in meaning, and my concluson is that they are exactly the same. Although "zwykle" more common word.
They both should be right. You would use one or the other depending on the gender of the person being sad.
That's what I thought. I guess it's a mistake on Duolingo. I checked the rest of my sentence first before commenting and everything else was fine, except for 'smutny'.
Both are put as starred answers, so it must've been a bug while marking your answer by the app, not a mistake on our side.
The literal translation for the word 'zwyczaj' might be 'habit,' so why not translate 'Zazwyczaj' as 'habitually' or 'out of habit' instead of 'usually?'