(I’m asking honestly.)
Another issue is that often GMO correlates with patentry, terminator seeds, IP lawsuits, and so on. But that's also a tangential issue.
The main issue is that, just like anything new, it puts us in the "beta testing in production" area, where the product being tested is "things which none of our ancestors have ever encountered, evolutionarily" and production environment is "our bodies".
Similarly, my understanding was that soil depletion (caused by farming methods) and crops optimized purely for high yield (via breeding or otherwise) are problems causing nutrition drop in foods. And that neither are problems solved simply by going organic or GMO free.
https://www.scientificamerican.com/article/epa-atrazine-herb...
There is a trove of studies showing the harm so I'm not sure you're being genuine. If you really can't find anything on Google I'll help.