As a one-off? Probably healthy. Little things like forgetting your birthday or breaking a vase.
As a habit?
Something’s wrong, and it might be the person ‘forgiving’. In cases of learned helplessness, they always try to portray themselves as perfect and forgiving. In fact, they enable bad behaviours, encourage evil people by being a doormat and get off on being the victim.
It’s an excuse to indulge repeatedly in grossly destructive behaviour by denying personal agency and forgiving the Evil figure who caused it. The opposite of saintly (scapegoating). And trying to claim status points by signalling afterward? Worse than the person they’re supposedly forgiving, they play everyone.
You should forgive something if it is entirely in the past and doesn’t matter at all anymore.
Otherwise, it’s foolish, because the conditions aren’t finished yet.