anyway, when baking lighting, light probes undergo what is called "tetrahedralization". It means Unity is going to spend time during the bake, to ensure that using the light probes in the actual world is going to be lightning-fast. You should use them.
Anyway I wasn't at the event, how many premade udon prefabs were in the scene? If the answer is more than "zero", you would have been better off implementing probes and getting rid of the prefab. seriously.