@codedayday Its a nice short solution. But I would recommend to take into account 2 things if you get to face this question in an interview.
You are using extra storage to store the string in lowercase (Space Complexity O(n)). You don't need to do this
You should mention during the interview that newS[::-1] its a built in utility from python and its time complexity is O(n)
Just as an exercise, try to solve the problem in place without using the extra list.
Anyways, I loved your short version!
Thanks for sharing :)