Is it free software?

Or even, in LICENCE.TXT or COPYING.TXT something as simple as

"It the opinion of the authors of this code, the output of any AI model trained on this code is a derivative work of this code. As such, we believe any and all output of such an AI model must be licenced under the GPL".

That would then make life somewhat risky for any bot-operator just slurping the web :-) EU/UK law says using slurped data to train your model is perfectly legal (imho they're explicitly treating it exactly the same as a human reading copyrighted books). But the law says nothing about the output (again imho treating it exactly the same as the output from a human who has read copyrighted books).

And that gives you as the author of the code extremely good grounds for saying "Well if you copy the code you should have checked the COPYING file. What! You didn't! More fool you!".

It's all very well for a defendant to say "there wasn't a copyright notice", but a lot harder to argue "innocent infringement" if it's a case of "I didn't look for a copyright notice"!

Cheers,
Wol