This seems like a pretty significant anti-trust issue. One of the two mobile OS makers is using a product from the other for its AI assistance. And that means that basically all mobile devices will be using the same AI technology. I don't expect the current US government to do anything about it though.
What antitrust rule do you think would be breached? I admit I don't see the issue here. Companies are free to select their service providers, and free to dominate a market (as long as they don't abuse such dominant position).
It also lends credence to the DOJ's allegation that Apple is insulated from competition - the result of failing to produce their own winning AI service is an exclusive deal to use Google while all competing services are disadvantaged, which is probably not the outcome a healthy and competitive playing field would produce.