It’s just the internet. Lemmy has features built in to reduce mod abuse like a public modlog anyone can view without logging in. IMO the reddit format was never good for discussing heated topics.
You can tell by color and how plump the top one is behind the flower. Also, unpollinated flowers will fall off. I’m not a botanist so I can’t tell you what the parts of the flower are called.
I read that this cactus was not self-fertile but brushing the flowers together has produced fruit. It doesn’t mean the seed is viable but I will try down the line.