When you kill a mob, or use experience bottles the xp orbs movement will stutter a lot. This seems to be due to desync between their physics on client and the server. This seems to have been introduced in 1.21 Pre-1.

Reproduction Steps

Method 1

• Drop an experience bottle (it's more severe if you throw it against a wall)
• Observe the orbs movement
  Minecraft 2024.11.10 - 16.01.10.05.mp4

Method 2

• Kill a mob & quickly switch to spectator (so you don't absorb the orbs)
• Observe the orbs movement
  Minecraft 2024.11.10 - 15.26.20.04.mp4

Observed Results

• The XP orbs abruptly change position

Expected Results

• The orb movement would be fluid and uniterrupted