Leona is a very strong character, that sees a lot of usage at high-level play on a lot of teams. Many players have trouble countering the character; if she scores a knockdown, she has a plethora of options to lock you down, and any incorrect guess can lead to nearly your entire health bar being diminished. She not only has a low that can be special canceled, an instant overhead that can be special canceled, but also an option select off of the low that can catch rolls.
However, as explained in this video, people are missing one of the most vital options on wake-up against Leona–that not only lets you escape her mixup, but also punish her should she attempt the 50/50–and that is backdash. Outside of characters such as Goro, Kim, K’, Hein, Chin, and Verse, every character can backdash and counter the mixup attempt. This forces Leona to dig a little deeper into her tool box to take rounds off of you.