When exploring an end city shortly after it is generated, shulkers can sometimes be seen floating in the air a short distance from the structure. This is by and large a visual issue, and the server will consider these shulkers to be located in a normal spot (i.e. attached to a nearby block on the exterior of the end city). The gameplay consequences of this bug are:

• players may unexpectedly collide with an angry air block which shoots projectiles at them
• players see a floating shulker that they cannot interact with
• oddly enough, the player may stand on the floating shulker, and would likely be kicked for flying on a multiplayer server

The shulker models will return to the proper location after a while, or immediately upon being reloaded.

To reproduce

In a new creative world, repeatedly teleport to end cities until you see a floating shulker. Most likely you will see one within your first 15 attempts.

/execute in the_end positioned ^ ^ ^10000 run locate structure minecraft:end_city

Note

Related to MC-83462 (WAI). MC-263391 is very likely the same issue as this and is unrelated to any mods the reporter had installed.

Also, I often hear shulkers teleporting when I first teleport to an end city, so it may be that the client occasionally thinks that the teleportation has failed when in fact it has succeeded on the server.