Mercy becomes corruption when it consistently protects the powerful from rules applied to everyone else.

Repeated leniency toward the powerful is not mercy, it is a second set of rules. When the same behaviour ends careers at one level and produces an apology at another, the standard has stopped being a standard and everyone below can see it. That visibility is what erodes trust, not the original offence.

Where you have influence, watch what happens to the rules at the top rather than at the bottom. That is where legitimacy is actually decided.