If you do not trust it there's a document Here which guides you through downgrading manually.
On linux This requires qt and curl to be installed, how it is installed depends on your distro, but it should work on windows out of the box.
To run this get a binary from Releases for your OS.
Read the build document
Cornelius Rosenaa for making this
Michel for testing on windows
SteamRE for DepotDownloader
Zerratar for reference FO4-Downgrader
feathericons for icons
yjg30737 for his PyQtLoadingscreen script