No, I don't have any ̌ with D. I have DÍTĚ. My answer and Duolingo's answer are the same (because Google gets same results).
Look: my answer - https://www.google.com/search?q=s%CC%8Cpatne%CC%81+di%CC%81te%CC%8C
Doulingo's answer - https://www.google.com/search?q=%C5%A1patn%C3%A9+d%C3%ADt%C4%9B
But there is something wrong with letters. For example, Unicode symbol of "my" š is s%CC%8C, and the symbol of "correct" š is %C5%A1
You are really using some wrong characters, they cannot be accepted. I do not know how you generate them, but you will have to find a different way.
Please look closely at the appearance of your letters:
They are clearly different, they look differently. You have to use some proper Czech keyboard layout, no matter if PC or mobile.