be no longer one's former self 判若两人

“判若两人”，汉语成语，形容某人前后的言行明显不一致，像两个人一样。可以翻译为“be no longer one's former self，have totally changed或have become quite a different person”等。

例句：

他对待我的态度和以前判若两人。

He treated me in an entirely different manner from before.