When curing villagers who are in a minecart using a splash potion of weakness and then a golden apple, the villager remains in the minecart during the curing phase, but once the zombie villager cures and turns into a villager it will hop out of the minecart and be positioned inside the ground block, one block below the correct position.

See screenshot.

I replicated this issue multiple times with the same result.

Also, I will note that the minecart with the zombie villager is placed on a rail when this happens. I am not sure if this happens if the minecart is not sitting on a rail.