What are 2 reasons GMOs are bad?

Could you possibly elaborate on two primary reasons why genetically modified organisms, or GMOs, are considered detrimental? I'm particularly interested in understanding the potential health risks they pose to humans and the ecological imbalances they might cause. Could you also provide any scientific evidence or studies that support these claims? It would be helpful if you could explain in a clear and concise manner, as I'm trying to form a comprehensive understanding of this topic. Thank you in advance for your insights.