I've been thinking about this as I do AoC with Copilot enabled. It's been nice for those "hmm how do I do that in $LANGUAGE again?" moments, but it's also wrote some nice looking snippets that don't do quite what I want it to. And many cases of "hmmm... that would work, but it would read the entire file twice for no reason".
My guess, however, is that it's a net gain for quality and productivity. Humans make bugs too and there need to be processes in place to discover and remediate those regardless.