Seed: 5450957878814971038

How to Reproduce?
1. Install snapshot 21w42a
2. Open Minecraft
3. Create a New World with the specified seed above
4. Open LAN and enable cheats
5. Use this command -> /tp @p /tp @p -1798.633 -9.88852 -149.055
6. Switch to Spectator [Mob Spawner will have a glitchy animation]
7. Switch to Creative [Mob Spawner animation will return to normal]

-Close this- Read CAREFULLY!

The spawner is flickering. It is not spinning as it usually does when in survival and creative mode. In spectator mode, the spawner animation is flickering. The mob spinning animation in the spawner is not the same animation as it does when you're in creative and survival game-modes.

Must Read: Test it out yourself before commenting or you're just commenting for the sake of commenting.

#RoadToHelper