The gm or non-gm commercially grown soybean can be used for seed, and do as well as the plant it came from. But holding back some harvested gm soybeans can be VERY costly:
https://grain.org/en/article/2240-monsanto-patent-fight-ensnares-missouri-farm-town
Commercial gm or non-gm corn doesn’t keep that ability. That’s why raising seed corn is so expensive.
That’s the biggest issue with GM. They’re patented. Monsanto(now Bayer) will sue you if you save seed. You have to buy it from them every year.
Now they’re starting to use CRISPR Cas9 gene editing to create better veggies but it’s the same, patented. When a handful of companies end up owning all food, that’s not a good thing.