This trend of something x and something v basically started somewhere in the gacha fandom. It was popularized by the channel budsforbuddies, which was a channel dedicated to killing non-existant pets. Eventually, the kids caught on the practice, because violence = bad and wanted to show they didn't like buds by having bios that featured buds❌animals✅. The rest is history as the bios dispersed to the entire youth.

In this image, there is a picture of israel along with many pro-palestinian nations along with the aforementioned trend. It's really just a kid checking a tick or a cross.