In 1.16.100 experience orbs were changed to float in water instead of sinking. Presumably this was intended to match the behavior of item entities in water, since both drop from killed mobs. However, experience orbs actually float .25 blocks above the surface of water because they have a mob collision box. This makes them behave differently than item entities:

• Experience orbs get stuck in most places where top slabs block water streams.
• Experience orbs do not sink when floating on or moving across falling water.

The attached test world, XP Floating Problems.mcworld, contains a labelled system of command blocks and water streams to automate testing this issue. The test area has four parts labelled with crimson signs and separated by black concrete lines. Only parts 1, 2, and 4 relate to this bug report (the issue shown in part 3 is reported separately because it does not seem to be due to the xp_orb collision box). Each water stream also has a number.

Steps to reproduce

1. Open XP Floating Problems.mcworld.
2. Stand on the gold block and face the test area. Note that the player must stay ~10 blocks from the test area to not disturb the experience orbs.
3. Press the button on the command blocks. This deletes all existing items and orbs and runs a new trial.
4. Examine the results. You may need to repeat steps 2-3 after examining each set of water streams because nearby experience orbs always move toward the player.

Expected result

In each pair of streams, the experience orbs end up at the same relative place as the items.

Actual result

• In stream 2, the experience orbs end up at the same place as the items in stream 1.
• In stream 4, some of the experience orbs end up at the same place as the items in stream 3, and some of the experience orbs get stuck on the slab.
• In streams 6 and 8, all of the experience orbs get stuck on the slab, but the items in streams 5 and 7 pass under the slab.
• In streams 10 and 12, the experience orbs float across the falling water and do not sink, but the items in streams 9 and 11 sink.
• In stream 16, the experience orbs float on top of the water source that has downward current, but the items in stream 15 get pulled down through the water source by the downward current.