I don't think anyone above said "bubble". Overvalued is a different thing markets are usually either over or undervalued and probably overvalued today. Bubbles proper are kind of rare, the last major clear one being the 2006 housing bubble. You could argue there's a bond bubble presently.

You're right - Claiming the markets are overvalued like the unicorn bubble isn't literally saying there is a bubble, it's just implying there is.

There is most likely a corporate bond bubble, as we know from representative market signals. With the S&P 500 though, four companies are not representative signals.