It's a question of whether copilot can be "creative". I'm mit sure, but it did manage to solve some of the harder leetcode questions here https://youtu.be/FHwnrYm0mNc and I'm curious how it will fare on the later advent of code problems.
This will not be easy to see in any kind of coding exercise. It is very hard to come up with coding problems with solutions that have never been written before, at least for a coding competition like Advent of Code. For example, we don't know of polynomial time solutions to the Travelling Salesman problem but it wouldn't make sense to have that as a coding challenge in Advent of Code, or Leetcode, or anywhere else.
Since nobody has ever produced a program solving such a problem, Copilot will not be able to produce a solution either, but it's not designed to do that anyway.