Welcome to the Community,
that's by design, but please don't ask me why. I'd really love to understand this myself.
Anyway, what you can do is to install ESXi 6.7, and then upgrade to ESXi 7.0.
André
@ Chris_Redz
Here's a new blog post regarding the OSDATA (VMFSL) partition size: https://www.virtuallyghetto.com/2020/05/changing-the-default-size-of-the-esx-osdata-volume-in-esxi-7...
André
Just wanted to add that it's 119.9 GB regardless of drive size, so it's 119.9GB on a 240GB drive as well as a 1TB drive. It just happens to be 50% for you.
Great solution, works fine.