Talking about someone behind their back takes zero courage. Saying it to their face, kindly, takes all of it.

Saying it to a third party costs nothing and risks nothing, which is exactly why it is so available. The same words to the person, said kindly, put you somewhere uncomfortable where they might be hurt or might disagree. Kindness is not the soft option here, it is the hard one with a softer delivery.

Pick one thing you have been saying about someone and decide whether it is worth saying to them. If it is, say it privately and plainly. If it is not, stop saying it anywhere.