From the article "Google said it is giving itself until 2029 to prepare for this event."

https://blog.google/innovation-and-ai/technology/safety-secu...

Reading between the lines I suspect the following:

- We’ve already demonstrated breaking 2048-bit RSA in tightly controlled lab environments

- It’s expected that will be possible at scale by 2029

- The US expects to have around 2 years of supremacy in the space before adversaries catch up