Is there any Idiom or provide verb that would imply " You cannot conceal such facts or issues"?
If, like the Americans mentioned in this good ELU answer, you don’t mind slightly mixing two metaphors/expressions (the ones about the elephant in the room and the 800-pound gorilla) and then using the result as a simile that, although unrelated to the strict meaning of either of the two originals, would nevertheless mean "such facts or issues cannot be concealed," you could consider:
(from ‘Labor of Love: The Story of One Man's Extraordinary Pregnancy’ by Thomas Beatie, via ‘Google Books’ where it’s used in “Hiding a pregnant man is like trying to hide an eight-hundred-pound gorilla.”)
cf:
Usage
The term refers to a question, problem, solution, or controversial issue which is obvious to everyone who knows about the situation, but which is deliberately ignored because to do otherwise would cause great embarrassment, or trigger arguments or is simply taboo.
The idiom can imply a value judgment that the issue ought to be discussed openly, or it can simply be an acknowledgment that the issue is there and not going to go away by itself."800-pound gorilla" is an American English expression for a person or organization so powerful that it can act without regard to the rights of others or the law.
The phrase is rooted in a joke riddle:
"Where does an 800-lb. gorilla sit?"
The answer: "Anywhere it wants to."
This highlights the disparity of power between the "800-lb. gorilla" and everything else.
The term can describe a powerful geopolitical and military force, or, in business, a powerful corporate entity that has such a large majority percentage of whatever market they compete within that they can use that strength to crush would-be competitors.
(The metaphor includes an inherent bit of hyperbole; the highest weight yet recorded for an actual obese gorilla is 600 lb. (270 kg). The average weight is 400 lb.)
The metaphor has been mixed, on occasion, with the metaphor of the elephant in the room.
(both from ‘Wikipedia’)
Truth will out
One way or another, in spite of all efforts to conceal it, the truth will come to be known.
Not too much of an idiom, but "The truth will come to light" has been used in this scenario since probably before Shakespeare used it in The Merchant in Venice (Act 2, Scene 2):
Well, old man,I will tell you news of
your son: give me your blessing: truth will come
to light; murder cannot be hid long; a man's son
may, but at the length truth will out.
The last part, truth will out has come to mean the longer phrase.
The cat will soon be out of the bag
The cat is out of the bag = The secret has been revealed
Let the cat out of the bag = to reveal a secret
The shit will hit the fan (warning: vulgar)
The shit has hit the fan = A scandal has erupted, the situation is a huge mess. This can also apply to revealing a big unpleasant secret.
However, both of these merely describe the situation. They do not directly admonish the person who is trying to keep a secret.
You can't keep it under wraps forever, or, You can't keep it under wraps much longer
The Free Dictionary
Concealed or secret, as in The design for the new plant is under wraps. This idiom frequently is put as keep under wraps, meaning "keep secret," as in Let's keep this theory under wraps until we've tested it sufficiently. It alludes to covering something completely by wrapping it up