This has been happening since shadowkeep but it's only become super prevalent recently, when I use whirlwind guard in pvp sometimes I will die to misadventure. It's always when people are shooting so I imagine there's some issue with me blocking locally vs me blocking on the server but it's not consistent. If it was just moments after blocking I'd chalk it up to latency but this happens when I've been blocking for long periods of time, sometimes upwards of two seconds, before the other play starts shooting me. That and the fact that it always labels me as dying to misadventure (still counts as their kill) makes me feel like there may be more to this than mere latency.