Comment by croemer

Thanks, that almost worked, needed the following (extra --force tap of core and link --overwrite)

  brew tap-new $USER/local-tap
  brew tap homebrew/core --force
  brew extract --version=3.3.0 htop $USER/local-tap
  brew install $USER/local-tap/cmake@3.3.0
  brew link --overwrite htop@3.3.0

Based mostly on https://www.ericbariaux.com/posts/brew_rollback/