according to Reuters, among the issues in the WGA strike is the relationship of the profession to large language models, which some (rightly, in our view as a technologist) call "plagiarism machines"
this is not the only issue but it is certainly an important and timely issue. writers tend to be among the first to fully understand new things, it makes sense that they'd be striking over it. solidarity.
A lot of people probably technically correctly will nitpick whether or not it's really plagiarism but you must remember the historical context. Much of what the current strike is about is streaming, which during the last strike was treated as an experimental new technology that amounted to five minute "webisodes" that couldn't amount to anything competitive with traditional TV. So the WGA made a lot of big concessions and now streaming has completely screwed over writers big time such that they're struggling to afford to live in the cities you have to live in to work in this industry.
This time around they're not taking any chances. There's a new technology. They're going to treat it as being the absolute biggest threat it could possibly be. If it could be used to replace a writer on their original show, or to replicate their tone, then even if it's not technically plagiarism it is still being used to eliminate union jobs. It might as well be a plagiarism machine.