What is juul flashing blue?

The JUUL flashing blue indicates that the battery is low. When the battery level drops below a certain percentage, the LED light on the device will flash blue four times to indicate that it's time to recharge the battery. This flashing blue light can be an early warning system to remind users that they need to charge their JUUL device soon. To charge the device, simply connect it to a USB charger or a JUUL charging dock.