The handwringing about the implications for open source codebases is also especially hilarious

I'm sorry to be the one to break this to you, but the answer to the question "does this mean people can now take my MIT-licensed code without attribution if I used a coding assistant?" is that they were already doing that, long before LLMs

If you're lucky, that will continue to be the case. If you're unlucky, then everyone will just vibe code their own solutions and your project will die in obscurity