Part of the reason Ubuntu has gotten a reputation for being easier to install is that it has contained a lot of non-free firmware for a long time. That site even says so (indirectly though).
As @StephenKitt mentions in a comment that post is so old that the Debian installation should have been based on Debian Buster (Debian 11), and non-free firmware only became included in Debian Bookworm (Debian 12).
And in any case firmware is unlikely to be the reason for such a massive difference.
I don't have the time to read through his entire blog (or whatever it is), so I'm just going to point out two major problems:
- He doesn't explain how he installed Debian
- He doesn't explain how he made the measurements
The tweet claims both are minimal, but we can't know. And "Debian Server" is not a well defined things, so the Debian might have had quite a few more things running.
My conclusion: That is as usable as a comparison between apples and oranges.