I think current co-pilot is less useful for person who entirely knows the language and libraries.
Right know I see more use for people who understand the language and libraries, but are frequently Googling ”how do I do xyz in P” (because they can’t recall certain things).
If you mainly deal with 1-3 languages on a daily basis that you have mastered, you don't routinely search for "How do I do xyz in P". Maybe if you're a junior or intermediate developer, or have a poor memory. But doing that frequently is a clear indicator that mastery have yet to been achieved.
It's not wrong or bad to search for help, but it doesn't indicate mastery of the language you're using.
Knowing a language or a tool doesn't mean you will always know the best or the smartest way to do something. This is not necessarily a test of your programming ability. And best practise is more often ever changing. Almost every language or tool is always ever changing and improving itself which best practise also keeps evolving.
Secondly you don't necessarily need to know or master a language or tool for every kind of work. You can just choose to learn as you go along with it, in which case knowing how to search and use the most effective way to do something is very useful.
Right know I see more use for people who understand the language and libraries, but are frequently Googling ”how do I do xyz in P” (because they can’t recall certain things).