I'm surprise Apple doesn't, even unofficially, upstream fixes to Homebrew before a new macOS version is released. Why let Homebrew break for so many macOS users

I'm surprise Apple doesn't, even unofficially, upstream fixes to Homebrew before a new macOS version is released. Why let Homebrew break for so many macOS users on day 0? I know Apple is secretive about unreleased products, but the type of fixes for Homebrew wouldn't reveal too many Apple secrets. Do Apple engineers not use Homebrew on their own Macs while developing macOS?