There is specific knowledge
If someone claims that there is specific knowledge about something you are in fact expected to accept her or his view of it.
This is not only a lie in the sense that I expect you to accept my view of my knowledge about someone’s claims.
It’s a statement that provokes self-contradiction per se in the sense that knowledge is somewhere, for instance, printed in books or published in papers. Knowledge, here, is understood as something that can be reasoned, explained, discovered, acquired, agreed upon, and verified, or at least falsified.
But, if there is such a thing as a view of knowledge, if there are people who believe to know something and who believe that others do not, then knowledge does depend on someone’s perspective.
Whenever I say “it is known that” or “we know that” I’d always rather expect someone else’s denial.
By the way, I find it very interesting to search Google for phrases such as “it is known that“, and “we know that“.