Nothing, beans are ok, one of best sources of protein for plant-based diets.

Biggest problem with soy is that 77% is consumed by animal agriculture, which is causing much harm in the world (deforestation, pesticides/herbicides, runoff, biodiversity loss, co2 emissions, ...).

https://ourworldindata.org/soy

The overuse of soy in the food chain has lead to high estrogen levels in about 50% of the population.