It’s different because licensed code on github and other websites is different from freely given code snippets on stack overflow.

A blog post is not permission to reproduce code with small changes. Neither is posting it under an open source license which usually require attribution.

quiz question: What's the license of code snippets on stack overflow?

No idea sorry but the implied idea of the site is that people will use answers and snippets without attribution.

Absolutely not the case with other OS code posted online.

It's under CC-BY-SA, which is very incompatible with pretty much everything else.

That’s funny, I guess everyone just ignores that, but legally it means AI should not be trained on it either since it requires attribution, I wonder was it always that way?

I think AI companies are just trying to ignore IP laws entirely, perhaps they’ll get away with it but there is bound to be a case where a small tool or game is 90% identical to a source reference at some point given the way these LLMs work.