Irrespective of the entire NOTICE file question, Apache license text is pretty clear that you MUST retain attribution notices, and I think most courts would consider the line "author = " to be a clear attribution notice.

And then there is the question of them slapping "Copyright Google LLC 2026" on every file. I'm not sure you can do that unless you have actually modified every file, and I think you have to say what exactly you modified and what is covered by the old copyright, and that presumably requires them to say what the old copyright is.