A good rule of thumb: if you wouldn’t say it in front of the person you’re talking about, don’t say it at all.
No, not all gossip is bad. If I’m being gossiped about, it may alert me to the fact that I’m acting inappropriately. The shame I feel will reorient me to right action. This sort of gossip is very useful to me, and protects those around me.
But done purely for entertainment, or done with malicious intent, gossip does just as much harm to the gossiper as it does to the person being gossiped about. Look closely, and you realize it creates toxicity in everyone’s mind.
Gossip isn’t going away. But we can each ask ourselves what our speech is for.