Don't think it has been mentioned so thought I would: https://www.fossil-scm.org/
It was, some posts above:
https://www.fossil-scm.org/home/doc/trunk/www/index.wiki
The concept and philosophy behind it might be interesting (though their "git vs. fossil" page is really biased*), but there's a fundamental objection to this SCM, and to all non-git ones:
Stackoverflow survey 2021.
I don't think this to be a case of "million of flies" - these are people who use tools for productive work, both independent workers or enterprise employees.
Possibly an exception could be made for mercurial or subversion, but in my personal experience, their user bases are also shrinking.
E.g: for work, I was recently involved in the migration of a (quite niche) FOSS from mercurial to git.
It went really smoothly, and both users and devs were happier in the end.
There was some internal initial resistance to the move from a couple of developers, mostly due to adapting to slightly different way of working, but nothing major.
One of them, in fact, was then tasked with laying out the new way of working with git (branching, tagging, and merging strategies) - and they made an excellent job.
* But they admit it. In Italy we say "oste, è buono il vino?" ("innkeeper, is your wine good?"), what answer do you expect?