This was in the original announcement[0] (1038 points, 17 days ago, 654 comments) https://news.ycombinator.com/item?id=46589675

[0]: https://blog.google/company-news/inside-google/company-annou...

> After careful evaluation, Apple determined that Google's Al technology provides the most capable foundation for Apple Foundation Models and is excited about the innovative new experiences it will unlock for Apple users. Apple Intelligence will continue to run on Apple devices and Private Cloud Compute, while maintaining Apple's industry-leading privacy standards.