As of April 21, 2022, Apple has discontinued macOS Server. Existing macOS Server customers can continue to download and use the app with macOS Monterey.
The most popular server features—Caching Server, File Sharing Server, and Time Machine Server are bundled with every installation of macOS High Sierra and later, so that even more customers have access to these essential services at no extra cost.
I doubt many people are running macOS Server installations at this point, so I don’t think this will impact a great number of people.
Thought they killed this off years ago! Maybe it was just their server line?