Sure but that doesn't mean it's under active development. Before that it was an ancient version of bash that hadn't been updated in years.

Yep, it’s been the default for a few years https://www.theverge.com/2019/6/4/18651872/apple-macos-catal...

zsh is the default shell for macOS Catalina and later.

https://support.apple.com/en-us/HT208050

no? I'm pretty confident I had to set it to zsh when I got a new mac a month ago