Certain villagers in my villager powered crop farm become farmers, plant a few crops, then lose their jobs. They will do this repeatedly, and this drastically affects the rates of the farm. Happens on my friends server, I have not noticed this problem in single player. The only other time this happened to me was in my villager trading hall where a villager became a librarian and then immediately lost its job. Then the villager would no longer get a profession. All these problems have happened in 1.16.1.