I think it's mostly in refernce to LGBTQ+ rights. They think that the only reason to have sex is for reproduction. So if you are gay, for example, you having sex with your preferred gender wouldn't result in procreation. So they think gay people with pride flags etc. are just sex obsessed perverts. Christian conservatives think that If you're a gay male teacher and you put up a pride flag in your classroom, you are just signaling to children that you love to fuck dudes etc. and not that you aren't ashamed of who you are.

Also chuds like to think all gay men are pedophiles etc.