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This meme is likely disingenuous. At the very least it is confused.
At the end of the Witcher 3, Ciri becomes a Witcher (the profession, a person who hunts monsters). The complaint is that she is a Witcher (a mutant, a person who has been mutated by monster dna), which doesn’t make much sense because she already has better-than-witcher magic powers, and is already able to drink Witcher potions (which she mentions at the end of Witcher 3, while not a mutant).
One issue from a legal/prosecutorial point of view (even assuming there is a willingness for the government to prosecute) is that the rules of evidence require authentication of documents. In the case of a whistleblower, they are themselves a witness and can authenticate (that is, attest to the genuine nature of) any supporting documents they bring in. If a whistleblower is killed, even if the government has the documents the whistleblower intended to authenticate, it becomes a lot trickier to use.