I think this comes from Conventional Branching, https://conventionalbranch.org, inspired by conventional commits (e.g. https://www.conventionalcommits.org/en/v1.0.0/)
But holy heck, I really have to argue with their literal first point. All lowercase, for what reason? It's never explained why they insist on a dated convention instead of proper style.
And in what world is "feat/" abbreviation considered allowable?
I lump this in with advice from people who put their source in a src/ folder instead of Source/.
For me, this popularity is graphable. Telling me it's a convention doesn't change that fact. I'm sorry.