It's actually from 1.21.3, but that doesn't appear as an option for me. Essentially what's been happening is that while me and a couple of friends, never more than 5 at a time, and sometimes when there are only 2, are on the realm we will suddenly have intense rubber banding. The realm then crashes and stays down for about 2 minutes. Upon reentering the world we are then sent back 30 minutes. This is not an exaggeration, it's always about 30 minutes of time that is lost from this bug. It seems to be unrelated to whatever the players are doing and more like the game just decides to quit on us, as it happens when people are doing more intense things like ancient debris mining, but also while people are just chilling in their own bases. It has happend 4 times in the last 3 weeks, but I'm sure if we'd been playing a lot it would have been more.