These days people like to call all kinds of things "Ponzi" and it's corrosive because it muddies the water.

Coins are not Ponzi schemes. Speculative bubbles, even if highly unstable, are not Ponzi schemes. Even scam tokens which are designed to rug pull, are not Ponzi schemes.

What is a Ponzi scheme? Paying yields to old investors from the principle of new investors. That's it. That's the definition.

When you see "risk free yields", Run. No exceptions.