This is a huge thing tbh. I don't like these AI things in general so I wouldn't use them anyway, but I just can't imagine going to my clients and asking them, "Hey is it okay with you if I routinely upload all your code to these random American venture-backed start-ups?". And I really can't imagine just doing that behind their back. I couldn't really imagine doing that with an employer's code either.
Ideally I don't even use software where accidentally toggling the wrong checkbox in some settings screen results in automatically uploading client code to these American start-ups either. Now I won't pretend that my stance against AI is purely out of some principled cybersecurity concern, but it's definitely a factor.