There is a page on the Hardware Dev Center where Microsoft outlines the CPUs that are supported for any given Windows release. The document is a bit confusing for end-users because it outlines the maximum supported processors for any given Windows implementation.
Specifically, if you have a 10th Generation Intel processor, then you will need to install at least Windows 10 1903 for Microsoft to officially support it. The same goes for the Ryzen 3000 series.
If you remember back to the Skylake era, Microsoft said that Intel’s Kaby Lake and AMD’s Bristol Ridge CPUs would not be supported on Windows 7 and Windows 8.x. Skylake was supposed to have reduced support in that same announcement, but Microsoft changed their mind after the backlash. Today’s news is basically the continuation of this, incremented a few processor generations.
I doubt this will affect as many people, because there’s less reason to hold out with Windows 10 1809 than there was to stick with Windows 7. It might be a bit of a problem in the enterprise, however.