Steps to reproduce:
Be on a dedicated server with operator permissions
Summon a monster that despawns on peaceful (for example a husk) in front of you
Go to the world options screen and click on the difficulty button serveral times
Expected result:
The difficulty not instandly changes when clicking on the difficulty button.
Actual result:
The difficulty instandly changes when clicking on the difficulty button. This makes the husk/mob in front of you (and all other monsters) despawn instandly once you reach “peaceful” on the difficulty button.
This behavior can lead to all monsters on the server despawning unintentionally when a server operator changes the difficulty (also named monsters or monsters riding boats etc.)
I reproduced this issue in 26.1-snapshot-5 on a LAN world.
While connected as an operator, changing the difficulty via the World Options screen applies the difficulty immediately on each click, rather than only when exiting or confirming the menu.
Briefly switching to Peaceful causes hostile mobs to despawn instantly, even if Peaceful is not the final selected difficulty.