I think the AI companies want a slowdown because they can't keep increasing the rate of improvements - or the amount of hardware it requires can't be built fast enough.

Of course, while they may be competing against each other, they're also competing with international competitors. China especially has or may have the capacity to scale up compute a lot faster once they get enough chip manufacturing power. They're likely preparing for it, and once they're ready they will take over real fast, like they did with solar and EVs.