In 1.13.2 basements of igloos have a Cleric and a Cleric Zombie.

In 1.14+ basements of igloos have a Plains Nitwit and a Cleric Zombie (which turns into Plains Nitwit after conversion).

I assume either of these reasons:

• The villager's code has been forgotten to change.
• The villager is locked up and thus cannot access the workstation.

Also when released the villager picks the cauldron over the brewing stand because the cauldron is closer to the villager.

I'd assume that the villager would also be a snowy type, since it is an igloo after all.