The Bug

Found while testing MC-271391 in 24w18a, however, this issue is likely to have existed before.

When you critical-hit a mob while it is in a small area surrounded by solid blocks, some critical-hit particles will appear black (like suffocating mobs).

Refer to the video attached.

How to Reproduce

Refer to the image attached.

1. Make a box that is 3x3 in size and two blocks tall. Do not use transparent blocks like glass. Dig out the middle so that you are left with an outline of blocks surrounding a 1x1 area.
2. Summon a mob inside of it, like a creeper.
3. Critical-hit the mob by jumping and then landing a hit on it while falling (preferably without a weapon).
4. Note how some critical-hit particles show up as black.