Can reproduce, also works with crossbow rockets killing entities and players, best way to solve it as a player is to either /kick, or if you wanna give perms later than /gamemode s unless it's a survival world, also kill them so they dont keep any items that they can use, and put it in a confiscations chest
They wont be able to do anything till u give them member and creative (or you can leave em in survival if you want),
Here's a solution idea. Code water so that when its placed or spawned it can not be collect for 4 or 5 ticks, which is enough time for a person trying to do a bucket clutch to release their finger. This could be done with block nbt, and remove the nbt any time the water is in a bucket to ensure that any water used for clutch actually works instead of instantly being able to picked up. The same could be done to lava as well but thats not necessarily a clutch.