From what I can tell talking to teachers, the public bullying among Gen Z has ebbed (excluding anything gang-related) but the private stuff is way worse. My guess is it's related, given how performative social media is and how much of an influence it has on Gen Z. Not saying Millenials are immune, but we came up in a society that actively cautioned against putting too much of yourself online whereas Gen Z grew up in a post-Facebook society that encouraged it.
Also, behaviors generally across the board are worse post-pandemic. It's apparently like no one knows how to be nice to each other anymore.