Anything that is traditionally rendered with Ray Tracing on stops visually rendering around the edges of objects that have transparent parts of their texture. 

Steps to Reproduce:

1. Join any world with Ray Tracing on, using the PBR resource pack provided below
2. Build a large area of Campfires
3. Look at an angle that places the first person hand above the smoke particles
4. Throw any throwable item in the direction of the particles (includes splash potions and snowballs)
5. Place an entity such as a zombie or skeleton with armour on and observe them at an angle that places them in front of the smoke particles

Observed Results:

Anywhere an entity has a transparent portion of their texture, the particles located behind them will not render.

Expected Results:

The particles should render, as there is a physical path for the player to see them. This is how it functions with Ray Tracing off.

You can download the PBR resource pack I used to take these screenshots and demonstrate the issue here:
https://www.mediafire.com/file/r4iatv86doxtxfo/Defined_PBR_v1.0.4.mcpack/file