Good question. I thought that only the 10-core Core i9 needs a new die, and everything down the line could be just rebranded 9th generation.
These Celerons have very low efficiency - 2C/2T @3.4GHz in 58-watt?!
Plausible and most probable. That new velocity boost feature is only available on 10 core i9s, which kind of support your thoughts.