The bigger problem is that your skills are weakened a bit every time you use an assistant to write code

Not when you factor in that you are now doing code review for it and fixing all its mistakes..

It depends how you're using it. I use it for boilerplate code, for stubbing out classes and functions where I can tell it clearly what I want, for finding inconsistencies I might have missed, to advise me on possible tools and approaches for small things, and as a supplement to the documentation when I can't find what I'm looking for. I don't use it for architecting new things, writing complex and specialized code, or as a replacement for documentation. I feel like I have it fairly well contained to what it does well, so I don't waste my time on what it does badly, and it isn't really eating away at my coding brain because I still do the tricky bits myself.