The particles for effects from beacons are reduced/faded. These particles become fully visible if other effects (with hideParticles=true) are added.
/effect give @s night_vision 100 0 true
Notice that fully visible particles are visible
Applying effect with particles hidden, then entering and leaving the area of a beacon/conduit with that effect shows the particles again
Splash/drinkable/lingering potion effects are ambient if applied while ambient effect is on player already