Quick answer: Unity ParticleSystem with velocity over lifetime modulation frozen when Time.timeScale = 0? VOL reads Time.deltaTime; pause stops it - use UseUnscaledTime in the module.
Time-paused boss fight; ambient particles freeze; want them to keep moving.
Use UseUnscaledTime
VOL module > Time Source = UnscaledTime. Pause doesn't affect.
Or animate via script
Set velocity manually using Time.unscaledDeltaTime. Independent of timeScale.
Audit pause-aware particles
Each system: pause behavior intentional. Document.
“Particle modules respect timeScale by default. Opt-out is per-module.”
If your pause UX includes ambient motion, the unscaled time pattern is the answer.