Alright, but even then I wonder who decided on that and why etc., I mean sure it's just a version number, but I wonder how I missed this change completely..

The PR is
https://github.com/bitcoin/bitcoin/pull/20223.
I wrote the change, and 12 other developers (including most of the maintainers) ACK'd it. It was also discussed multiple times in some issues and on IRC.
The why is primarily to stop the constant questions of "when 1.0" every time a release is made. Additionally the change aligns the version number with our actual process (we were incrementing the minor version number for versions designated as major releases) and how many people perceive the version number (I see a lot of people who wrote and said the version number without the leading 0).