that's a new one on me!

That's a new one on me! AND That's news to me. (This is the first time I've heard of or seen that. That is truly amazing, I did not know that.) — Это что-то новенькое. Первый раз такое вижу / слышу. ≅ Ну ничего себе! ≅ Ну ни фига себе! ≅ С ума сойти! (удивл.)

Something that you say when someone has just told you about a surprising fact or idea that you have never heard before

Example 1: And you eat cheese and peanut butter together? That's a new one on me! (thefreedictionary.com)

Example 2: Sue: All of us will have to pay our taxes monthly from now on. Mary: That's a new one on me! (thefreedictionary.com)

Example 3: And he told you he did a lot of cooking, did he? Well, that's news to me. (CID)

Example 4:
Sally: The telephones are out. None of them work.
Bill: That's news to me.
(McGraw-Hill Dictionary of American Idioms and Phrasal Verbs)

Example 4: A talking camera? That's a new one on me. (Dictionary of American Slang and Colloquial Expressions)