The bug

The particles from a spyglass have no texture. This is inconsistent with other items.

How to reproduce

1. Run the command below to summon a panda with a spyglass:

   /summon minecraft:panda ~ ~ ~ {HandItems:[{id:"minecraft:spyglass", Count:1b},{}]} 

2. Wait until the panda begins to eat the spyglass
3. Notice that the particles have no texture

 
If the panda drops the spyglass before it eats, you'll have to run the command again to get another panda.

Alternatively, you could run the command:

 /particle minecraft:item spyglass ~ ~2 ~ 1 1 1 0 30  

Video

A video of this issue can be found here: https://youtu.be/aZk518eHmK8