Here is a very simple way to reproduce the bug (1.14.4) : Make a container for 2 or more villagers (you can make it out of glass so you can see the profession of the villagers), then put down a work station which is 10 or more blocks away from the containers, and break and replace the work station quickly several times until you see that all of the villagers become whatever the profession is. At the end you can leave the workstation placed down, then release the villagers, and they will all go and work at that work station. This is related to the possible bug that novice villagers won't immediately lose their profession if a work station placed more than 8 or 9 blocks away is broken.
William Leber
Here is a very simple way to reproduce the bug (1.14.4) : Make a container for 2 or more villagers (you can make it out of glass so you can see the profession of the villagers), then put down a work station which is 10 or more blocks away from the containers, and break and replace the work station quickly several times until you see that all of the villagers become whatever the profession is. At the end you can leave the workstation placed down, then release the villagers, and they will all go and work at that work station. This is related to the possible bug that novice villagers won't immediately lose their profession if a work station placed more than 8 or 9 blocks away is broken.