According to this source, 77% of soy production is used for animal feed. That only a small percentage of it goes to cattle is irrelevant in terms of the damage caused.

Which is my point from the beginning. Soybean production is worse than beef production for the environment when it comes to South America.

It depends on what you are talking about exactly.

Does soybean production as a whole, in SA, is worse than beef production as a whole in SA?

Maybe.

Does soybean production for direct human consumption is worse than beef production for direct human consumption?

Not. Even. Close.

https://www.wri.org/insights/truth-about-low-emissions-beef

Basically you're average meat-eater is indirectly eating more soy than someone having scrambled tofu everyday