I found a ruined village in the desert, the one with destroyed homes with holes replaced with cobweb, and all of the villagers were zombie villagers. I found a row of three homes all next to each other, with cobweb 1 block in front of the outside of the door in the ground, and every time I tried walking against the wall into any of the rooms, I would take around 3 hearts of damage in 3/4 iron armour, no boots. I relogged, and there were zombie villagers stuck in the cobweb. It appears there is a glitch with zombie villagers in cobweb being invisible the first time you load the chunk or world. This did happen on my first loadup of the world. I do not have any video proof of this incident.