Yes, this happened to me. I had befriended an IP, turning it into a city-state. Before I could get my missionary down there, an AI rival had sent its military to the CS -- conquered it -- and started the multi-turn raze. In Civ3/Civ4/Civ6, razing is instantaneous. In Civ5/BERT and now Civ7, the raze takes multiple turns.
In previous games, though, if an AI captured one of my cities and started the raze, it was possible for me to recapture it and stop the raze. I hope that still happens in Civ7 (I haven't lost a settlement yet). I would be even happier if it were possible for me to recapture the city-state, "liberate it", and stop the raze.