The Ryzen 7000X3D series is real, according to what is said to be a leaked slide from AMD's client product roadmap. AMD's  processor roadmap will still include 3DV Cache technology.

 The 3DV Cache technology was a big part of how AMD's "Zen 3" microarchitecture from the previous generation could match or beat Intel's "Alder Lake" in gaming performance, with a performance boost of between 10 and 25%. The bar is set high for 3DV Cache to pull off another miracle with "Zen 4".

The popular desktop platform will get an update that includes 3D V-Cache (X3D) versions, which are listed as TBA (to be announced). Since the Ryzen 7000 series just came out yesterday, you might think that the roadmap is pretty new. Also, AMD's Ryzen G-Series should get a new version next year, probably in the form of the Ryzen 7000G series. We can only see a block starting in the second half of the year, which suggests that 5000G will be replaced by then. But it looks like AMD still wants to keep some 4000/5000G series around, so it is clear that AMD has not said goodbye to the AM4 socket yet.

Ryzen 7000X3D Series Mentioned in Leaked AMD Roadmap