I believe the right time to speak up is when you discover the lies. Not instantly objecting to the ongoing lies is the reason why they think it's okay and that they can get away with it. I know you advocate for speaking gently and with loving kindness, but the problem is that liars in this society will still perceive it as an attack, no matter how softly and lovingly the truth is expressed.

Lastly, it cannot be beneficial to everyone. Truth cannot benefit deceivers. Instead of always treading lightly to avoid hurting their emotions, let us also consider the people who have been brainwashed by the lies.

I think it's enough to talk politely. The fear of offending someone's emotions is one of the reasons why people with good values hesitate to speak the truth, as they are afraid of being demonized.

Evildoers will always exploit the emotions of good people against them.