A fact is an actual occurrence, so it is potentially verifiable, but so what?
It may be a fact that there is a human-like life form on a distant planet. one day we would expect to be able to verify that, if it is factual, but not today.
So I say "It is a fact that there is a human-like life form on some other planet in our galaxy. "
Is my statement a statement of truth, or fact?
You say it is a subjective belief, so it is my truth.
I say, no, I have a intuitive certainness concerning this, it is an actual occurrence, and one day it will be verified, so it is a factual statement.
Certainly there are many facts, recognized by some, denied by others, that were later verified.
Simply because a fact is not now verifiable, does not mean it is a subjective truth.
Existence is not one moment subjective, instantly transformed to an objective fact, simply because of an event in the mind of a particular human.
As for verification, there are many things I may verify to my satisfaction, that does not satisfy your requirements.
Saying that a fact is verifiable is begging the question.
No such requirement is necessary.
A fact is an actual occurrence, and it may be recognized or not, may be verified or not. Saying it is potentially verifiable is again begging the question, because if we do not agree on the verification process, the statement is meaningless.