The positions of xp_orb sync only once.

Sometimes, the client-side position does not match the server-side position.

Reproduce:
1. Find a platform large enough.
2. Execute this command many times: /execute @a ~ ~ ~ summon xp_orb ~6 ~ ~
3. Most of them will be absorbed immediately. The rest will take longer.
4. Execute /execute @e[type=minecraft:xp_orb] ~ ~ ~ summon minecraft:arrow
5. Check the positions that arrows just spawned. These positions are xp_orbs' server-side positions.