This is a bug that has existed since 1.16.210, when attachable items were implemented. The "breathing bob" of items with attachables applied (bows in vanilla (currently not noticeable due to other bugs), shields, tridents, crossbows, and spyglass) appear to bob up and down slowly. It appears to be slower than the default items and too large. Also, you can adjust the speed by changing the "n" in Math.sin(query.life_time * n), but due to the specification of query.life_time, it will be out of sync with other items. Also, there is a lack of X Rotation Animation.

Vanilla:

"rightitem": {
  "position": [ 0.0, "variable.bob_animation * math.sin(q.life_time * 45.0) * 0.5", 0.0 ]      }

Fixed(I don't know if this is correct or not, as I just identified the values from the animation times of other items.)
We have updated the code in the description as we have found more accurate numbers than before.

"rightitem": {
  "position": [ 0.0, "variable.bob_animation * math.cos(query.life_time * (360 / Math.Pi)) * 0.1", 0.0 ],
  "rotation: [ "variable.bob_animation * Math.cos(query.life_time * (360 / Math.PI)) * Math.sqrt(2)", 0.0, 0.0 ]
}

Test V

(Sorry for the multiple edits. I had to re-edit many times because I forgot how to write or update some of the code.)