I found out my close friend talks about me behind my back… and now I don’t know how to act around them

Something happened recently that I can’t stop thinking about. A mutual friend casually mentioned something that made me realise one of my closest friends has been talking about me behind my back. Not something huge or dramatic… but enough to feel like a breach of trust. Things like judging my decisions, making small comments about my habits… stuff they’ve never said to my face. Now every time I talk to them, it feels different. I keep wondering what they’re actually thinking versus what they’re saying. And the weird part is, they still behave normally with me. Same tone, same jokes, same conversations. I haven’t confronted them yet because I don’t want to create unnecessary drama if I’m overreacting. But at the same time, pretending everything is fine feels fake. I don’t know if I should bring it up, distance myself slowly, or just ignore it and move on. What would you do in this situation?