Certain particle effects appears very bright using Fabulous.
Repro steps
Using Fabulous, place a campfire. Observe that intersecting particle clouds will appear bright.
Turn down Render distance to something low, ~2-3.
Move backwards.
Observe that as the campfire is swallowed by fog the particle clouds will be bright, almost white, and be visible longer than the campfire model.
Can confirm. This is not an issue in 1.16.5.