Official News https://genshin.mihoyo.com/en/news/detail/6536
Oh so this was in addition to the Barbara event they were doing right now. I thought it was a reminder for people who weren't AR 20 yet. Good to know.
This character already has everything~! A cute and catchy name with a beautiful design :) I just hope I could get to play her in-game ASAP. Thanks for sharing the info!