Creepers in Peaceful

Me and a friend were playing on our server. I was afk and had set the game to peaceful previously. When I came back, I had died to a creeper along with two of my cats. My friend says he saw it happen, and when I thought I made a mistake in changing difficulty, I went to fix it and it still said peaceful. (Quick extra detail, I think I was low on food when I came back, which isn’t a thing in peaceful, though I’m not 100% positive.)