results = { { type = "item", amount = 10, name = "yeast", probability = 0.8 } },
results = { { type = "item", amount = 2, name = "yeast", probability = 0.1 } },

I don't think this is the correct way to define the yeast-cultivation recipe, in game you only see the second result, so it's pretty much a net negative recipe currently

What do you think is the correct way?

The expected value that you seem to be aiming for is 0.8*10+0.1*2==8.2 per craft, so just remove the second line and make first 0.82 probability

actually there's a better fix, I'll include it in the PR