Rather than encourage better behaviours of those targeted by the mob, it would be better to encourage better behaviours of the mob itself.
Forgiveness is absent in every social media or comment section and yet it's one of the crucial ways we get along with people. Having others visibly but perhaps silently forgive another would allow social proof that its okay to forgive this perceived offender. Forgiveness also allows a person to signal a change in views.
Where before they would only be able to signal disapproval, now they can still pile on and be toxic but then later signal forgiveness. Not being able to correct and reflect upon your own potentially negative actions would be one of the aims. By forgiving others you can forgive yourself of past negativity.
Forgiveness might say "I recognise you did something wrong. I do not expect public repentance, but I forgive you and go about my life feeling better".