The power to pardon criminals is a longstanding prerogative of monarchs, presidents, and others occupying the top executive position in a national government.
It used to go like this:
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Subject/Citizen: Your majesty/honor, I plead for you to investigate the case of <name>, who is in prison after being convicted of <crime>, which was a manifest miscarriage of justice.
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King/president, to the chamberlain/attorney general: That sounds bad; look into it.
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<Later>
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C/AG: Yes, it turns out the whole thing was a travesty. Here are the reasons for our opinion; we recommend clemency.
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<Later>
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K/p: This was terrible! I pardon <name> and command his immediate release.
In the United States, this isn't necessarily how it goes. Starting with president Gerald Ford pardoning former president Richard Nixon, and lately president Joe Biden pardoning several members of his family and government officials serving under him, we've seen pardons of the form "I hereby pardon <name> for anything he might have done."
Even kings of yore would be astounded at the chutzpah.
I suggest the following as an amendment to the US constitution:
The pardon power mentioned in Article 2, Section 2 cannot be applied except in the case of a person who has been tried and convicted of an offense against the United States. A pardon purporting to apply to any unspecified, hypothetical actions is repugnant to any idea of justice, and is void.