What happened to Ryzen 9 4950X or Ryzen 7 4800X?

Now that AMD has launched its much-ballyhooed Zen 3 launched October 8 , it’s time to clear up the confusing naming scheme that has existed, and sadly persists, with the debut of the Zen 3-based Ryzen 5000 chips.

You would be forgiven for wondering why the CPUs that will replace the popular Ryzen 3000 chips aren’t called Ryzen 4000. For example, rather than seeing a Ryzen 9 4900X replace the Ryzen 9 3900X, AMD will instead call it a Ryzen 9 5900X.
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https://www.pcworld.com/article/3584463/why-amd-calls-it-ryzen-5000-instead-of-ryzen-4000.html