Clean code is code you and others can understand and everybody seems to have a different idea of that. Sentence long variable names I don't like, they slow me down when thinking about or remembering what to do I'm not sure you can remember the names without Intellisense/IntelliJ autocomplete. I don't think I would enjoy working on this codebase.
Longer variable names are certainly a facet of Clean Code. It's in chapter 2, and Chapter 1 is an introduction.
That said, I strongly suggest Arlo Belshee's series https://www.digdeeproots.com/articles/naming-as-a-process/ - this gets to the heart of how to have both descriptive and not-sentence-long.