I'm not surprised. Disney has been behind copyright extensions in the US forever.
Just as a vweu superficial copyright overview /"what-if" exemplars including rpg impact ( disclaimer: IANAL, YMMV, etc)
1790 copyright -14yrs that can be extended one time
The public domain had most things pre-2011(>14yro and everything pre-1997 (>28yro). In that world pretty much everything d&d prior to 3e would be public domain, as would the early editions of GammaWorld, Gurps, Hero, Shadowrun, Traveler, WoD, etc along with all the artwork. The old-school world could reprint and/or modify actual "old school editions" legally.
LLMs could be built on a "current-ish" public domain data set (on par with the "Random Grandma" in keeping abreast of current events) and then enhanced with copyrighted works by people who own/license it to be more specifically informed.
And if you, as an individual, tried to make a service where people paid you money to make rip-off art of Disney characters newer than Hunchback of Notre Dame or Toy Story 1 , you absolutely would be sued into oblivion when Dusney notices you.
1976 authors life+50yrs/75yrs work for hire
This is a world where maybe the 1974 first edition d&d was public domain if it was a work for hire, otherwise that would be protected until 2059 (Dave Arneson's death in 2009 +50yrs). No other RPGs would be public domain.
LLMs based on public domain would be limited to data from the 1950s, could generate WW2-era and prior artwork, would know about Mickey Mouse and the Loony Tunes, and would be capable of doing customer service work (augmented appropriately with current product info) but not "search", would have issues with modern terms (i.e. cell phone, laptop, tablet) and would likely be incredibly racist, sexist, and very anti-communist. Programming assistance would be custom per language/compiler or need to be GPL-based.
And if you, as an individual, tried to make a service where people paid you money to make rip-off art of Disney characters released after Cinderella (1950), you absolutely would be sued into oblivion when Disney notices you.
We currently live in the "life+70yr / work for hire ~95yr" universe. Meaning 1930s era. LLMs trained on public domain works should sound very outdated and say "23-skidoo!". Betty Boop would be available, I think.
So if an LLM doesn't sound like a mobster or a WWI news reel, if it knows what a jet plane is, that rock & roll exists, or it assumes that "non-whites" can go anywhere in America a "white" person can go, its almost certainly trained on copyrighted works without permission.
And if you, as an individual, tried to make a service where people paid you money to make rip-off art of Disney characters, you absolutely would be sued into oblivion when Dosney notices you.