Leona had a bug. 57% winrate.

That's because Leona isn't a hard carry. As much as people may have disliked Leona's bug, Yasuo's bug let him 100-0 people even faster/earlier while Leona's bug only gives her a good win rate if her team is competent.

How many of our games is Leona in opposed to Yasuo? Honestly, I haven't seen a Leo in months.

Youre forgetting the extra special ingredient of a fun game: fun.

A broken Yas that can merc youre whole team more unfun than a broken full tank supp.

Some champs' kits are just annoying and unfun despite numbers. Teemo's a good example of this. Yas and Ekko are too.

wasnt the bug introduced in 6.2 when people werent grinding for their elo. also it was just a long range stun that was caused by her zenith blade. best visual would be if you had 3 stacks from a tahm and he tonged you.
it wasnt a 100-0 hard carry bug.

No I understood your point. :P I was just recounting that Leona's play rate definitely increased during the period in which she had a bug and pretty large chunk of the community was aware of it. But I agree that Yasuo is seen 100x more than Leona which is definitely a part of the reason everyone is so much more upset by his bugs.

Yasuo= overloaded kit

Leona= not overloaded kit

see the difference?