Is the sentence “what was the best food you have tried in Japan so far?” Grammatically wrong. Apps tell me yes, but I hear it in everyday life.

In English learning apps, they said I was wrong when I wrote “what was the best food you have tried in Japan so far?”

They said it was meant to be “what was the best food that you have tried in Japan so far?”

Question: in day to day life, i see people talk like this all the time. “What was the best song you heard during the concert?”, “what’s the best restaurant you’ve ever been to?”