@incomingstatsPhD I agree with @MathStat. Email the dept you want to attend immediately and explain your thinking. I think depts respect the april 15th deadline in the sense that they will not try to actively recruit students who have committed after that deadline, but if the decision to change is coming from your side, I think depts will be open to it. Especially with the covid situation, things are already in flux (some intl students may not be able to get visas, etc.), so there is a chance they are open it. You will obviously need to tell the school you committed to already, but I do not think they will restrict you from changing your mind.