Shor’s algorithm can. What is speculative about that?

I put the word "some" in front of "crypto" for a reason.

There is some crypto that we know how to break with a sufficiently large quantum computer [0]. There is some we don't know how to do that to. I might be behind the state of the art here, but when I wasn't we specifically really only knew how to use it to break cryptography that Shor's algorithm breaks.

[0] https://quantum-journal.org/papers/q-2021-04-15-433/