Well, Google decided to stop publishing their research after losing the battle to ClosedAI, which Google themselves started (the transformer paper that Google researchers wrote in 2017). So it's reasonable to think that companies are not going to compete with ClosedAI by being open about their latest achievements until they have something comparable to show. They might have achieved incredible success in terms of inference speed, but not in the quality of responses.

It's also possible that they're waiting to see how the regulation landscape changes. Big tech like Google and Meta are under much more scrutiny than a small company like ClosedAI, so they might need to solve legal issues before they can unleash their models. For example, Meta didn't release LlaMA for commercial use partly due to legal reasons. I've heard they're working on the next gen LlaMA w/ commercial license. I hope that happens so that ClosedAI realizes they can't enjoy their monopoly for long unless they become more open about their products.