Not the first time I've heard this. There was a leak that was very quickly deleted where it mentioned Valve were using some type of custom GPT for calculating physics (instead of for LLMs). So instead of doing actual complex physics calculations for environmental destruction, a GPT type AI would be doing it.

Obviously its to go in tandem with their current physics, just offloading specific stuff to the AI. It's apparently very good.

Source is trust me bro, but we'll find out soon enough I guess.