The bug

If a spawner is set to spawn lightning bolts, a full lightning bolt is displayed, unlike miniature models of entities as usual in a spawner. Previously, lightning bolts were not rendered and could not be spawned using a spawner, but that has since changed, and now a full lightning bolt is rendered, spinning around the spawner.

When a player leaves the area around the spawner, the lightning bolt freezes in place. While looking from certain angles (upwards) at this frozen lightning bolt, it can become invisible.

The expected behavior is that either:

• The lightning will not render at all and will not be spawnable by spawners, or
• The spawner will render miniature model of a lightning bolt instead of a full-sized one

How to reproduce

1. Run one of the following commands based on the version you're using:
   1.17.1 and older

   /setblock ~ ~-1 ~ minecraft:spawner{SpawnData:{id:"minecraft:lightning_bolt"}}

   21w37a and newer

   /setblock ~ ~ ~ minecraft:spawner{SpawnData:{entity:{id:"minecraft:lightning_bolt"}}}

   A full lightning bolt is shown

Video

Click this link to view this bug: https://youtu.be/kOufLlgOC3c

Additional information

• This bug was not present in 1.15.2
• This bug was present in 1.16.1
• The spawner in the video attached has had data values changed to accelerate the speed at which it spawns lightning bolts