TL;DR: The big tech AI company LLMs have gobbled up all of our data, but the damage they have done to open source and free culture communities are particularly insidious. By taking advantage of those who share freely, they destroy the bargain that made free software spread like wildfire.
A lot of open-source software uses copyleft licenses like GPL. If a company uses that code to build its own products, then some or all of their new code may also become open source. This is an important part of how open-source projects stay open. Organizations like FSF have taken big companies to court over this and won.
AI companies trained their slop-generators on that open-source code. In many cases, it will reproduce it line-for-line. But courts currently hold that the generated code is no longer subject to the original copyright restrictions. It’s nearly impossible to publish open-source software without being scraped for AI training.