Lactones are generally recognized as harmless, but tofu with lactones is particularly tender (it is difficult to pick it up by hand). It's easy to tell in the supermarket. Generally, it is sold everywhere, and you can hold it in your hand, not lactone tofu. Harmless, as long as it is normal tofu, whether it is brine or gypsum, it is harmless to human body.
Because ordering tofu is a chemical change, the brine itself is toxic, because it is a mixture of magnesium chloride, sodium chloride and magnesium sulfate, but in the process of ordering tofu, the chlorine in it replaces the calcium ion in soybean milk, and the brine itself is no longer brine, so it is non-toxic. Of course, chemical changes have a quantitative problem. If there is too much brine, it will indeed make tofu toxic because of incomplete reaction, but if there is too much brine, tofu will turn black and fools will not eat it. The white tofu you see must have completely reacted with salt water. As the old saying goes, "Bitter water makes tofu, and everything drops."
Gypsum is calcium sulfate. It is worth mentioning that gypsum itself can be used as medicine. You said it was edible, but using gypsum to solidify soybean milk is different from chemical changes.
The difference between brine and gypsum is not the harm to human body, but the gypsum-flavored tofu will put more water in the tofu to make it contain more water. This kind of tofu tastes tender and not delicious, but it is weighed when there is more water. So now some businesses use plaster to make more money. It is also a kind of knowledge, and the dosage is very important. Therefore, it is said that "there are three difficulties in the world, punting, while the iron is hot, making tofu."