Have you taken a look at the accounts participating in these contests? It's quite disturbing as they do nothing else beside enter them. Like quite literally just that. Seems like you have a sockpuppet farm on your hands most likely most of the accounts being run by the same person. I'd suggest making entries require a bit more than whatever some of these accounts do, example:

@ayahdindin/comments
@ghinamidrara/comments

etc

I didn't even look at all of them, these were 2 out of 3 I looked at but it seems quite obvious what's going on here and I don't think a couple people farming these collage contests should receive the post rewards these posts earn.