The universe is not a black hole because the "Schwarzschild radius equation" only applies in a very specific/narrow circumstance, namely a perfectly spherical, non-rotating mass surrounded by vacuum in flat spacetime.

Applying that equation to the observable mass of the universe violates basically every single requirement needed to apply the equation.

Often it's taken out of context by pop sci channels to propose the universe "could be" or even "is" in a black hole. But from my understanding, as a non-physicist, it's not surprising or interesting to most physicists that the math works out like this, and there's nothing else to suggest that we're in a black hole.

I don't think it means anything, it's probably just a curiosity. Simple equations like that probably don't work correctly when applied universe-scale.