Villagers do not have 2 levels. When we call the villagers they immediately have iron, but there must be a stone and they do not have emerald, that is, 4 levels.
Sorry for the mistakes because I am translating from Google translator and if something is not clear ask me.
Villagers are missing 2 trade tier badge textures. When we spawn villagers they initially have iron badges instead of stone, and when you unlock their tier 5 trades they still have diamond instead of emerald badges.