Traditionally, yes, to be a tea it must be made with camellia leaves (usually sinensis, but sometimes taliensis). Anything else is technically a tisane or an infusion, not a tea.

But that only matters if you’re a tea snob ;)

I know, that’s surprising. I live in Japan and saw many different types of teas.

About the black beans tea, here is one article if you’d like some reading: https://senbirdtea.com/5-health-benefits-of-kuromamecha-black-soybean-tea/

Also, I had gobocha here, which is made off of dried roots, and my wife makes some tea with dried mushrooms.

Maybe those are more like infusions to be honest, but the Japanese word to describe those drinks is “cha” which is basically tea.