My friend talks differently about me when I’m not there

I recently found out something that I can’t shake off. A friend of mine — someone I’ve trusted a lot — apparently talks about me differently when I’m not around. Not directly insulting… but subtle things. Comments that change how others see me. I didn’t believe it at first, but I’ve heard it from more than one person now. And the strange part is, nothing has changed in how they act with me. Still normal. Still friendly. Which somehow makes it worse. Because now every conversation feels a little fake. I don’t know if I should confront it or just slowly distance myself. But it’s hard to trust things the same way now.