I'd like to see someone try to prove this. How many space invaders projects exist on the internet? I'd be hard to compare model "generated" code to everything out there looking for plagiarism, but I bet there are lots of snippets pulled in. These things are NOT smart, they are huge and articulate information repositories.
Based on my mental model of how these things work I'll be genuinely surprised if you can find even a few lines of code duplicated from one of those projects into the code that GLM-4.5 wrote for me.
animation: glow 2s ease-in-out infinite;
stuffed it verbatim into google and found a stack overflow discussion that contained this: animation: glow .5s infinite alternate;
in under one minute. Then I found this page of CSS effects:https://alvarotrigo.com/blog/animated-backgrounds-css/
Another page has examples and contains:
animation: float 15s infinite ease-in-out;
There is just too much internet to scan for an exact match or a match of larger size.