Earlier quoted context omitted.
Genetic modification often produces altered proteins. These protein signatures do not match human T-cell allowlists, causing immune response. Even if the modification is a simple addition between adjacent start and stop codons, that kind of modification could alter meta encodings that control other aspects of cell regulation, including (potentially) gene expression -- which would cause proteins that are coded for but…
You know genetic modifications occur literally all of the time in everything we eat, right?
Normally, parallel evolution of people and crops allows humans enough time to adapt to natural mutations. Note selective breeding doesn't increase the underlying mutation rate - that's the number that I'm concerned we've manipulated beyond acceptable bounds.