The Bug
Experience Orbs within spawners are 2D which is inconsistent with other entities in spawners which are all 3D. This causes them to be small and un-viewable at certain times during there rotations.
/setblock ~ ~ ~ spawner{SpawnData:{entity:{id:"minecraft:experience_orb"},Delay:1s}}
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Hi there!
I can confirm for snapshot 20w30a and release 1.16.1.
Can confirm in 21w03a.
Can confirm in 21w05b.
Can confirm in 21w06a.
Can confirm in 21w07a.

intentional: if you summon a experience orb with commands or somehow managed to get something to drop the experience orb, it will face you wherever you face it which means it is 2D
Can confirm in 21w13a.
Can confirm in 1.17.1.

This command does not work in 22w05a due to a change in spawner's NBT. So here's a modified command:
/setblock ~ ~ ~ spawner{SpawnData:{entity:{id:"minecraft:experience_orb"},Delay:1s}}
OLD COMMAND:
/setblock ~ ~ ~ spawner{SpawnData:{id:"minecraft:experience_orb"},Delay:1s}

Confirmed for 1.18.1.

Confirmed for 1.18.2 Pre-release 1.
Can confirm in 1.18.2 and 22w11a.

Affects 22w12a
Can confirm in 1.19.
Can confirm in 1.19.2.