@guoyungui , agreeing with @ErnieS0 , you need to tell us 1. your visa status ( which visa F-1/ H1/J1 or ??); 2. when did you enter the country ( and obviously why you think you are a tax resident) ; 3. which country are you from and 4. exactly which treaty condition are you forgot to assert for 2021 tax year. As you are undoubtedly some countries have time limitations , some have status / intent limitations for assertion of treaty benefits.
I will circle back once I hear from you
