I started a 1.18 experimental world on my iPhone XR a couple of days ago and I have noticed some issues where any placed boats are in the loaded chunks, after logging out and then back in the boats disappear.
The same comes with villagers. Any villagers that are within loaded chunks as I log out will then have disappeared as soon as I log back in. I know it’s only within loaded chunks due to the fact that I have loaded a village which is where I got some of my villagers from, for which the village is out of my loaded chunk zone and those villagers are still there but the villagers I took from there are not. They simply despawn.