In Auto Racing, the light blue flag is not used as much but is still present today. It only comes out when the driver is leaving the pits only if traffic is approaching on the track or to allow the following car to pass at the earliest opportunity. Other times it is in place of the blue flag (with yellow diagonal stripe) and the blue flag (no yellow diagonal stripe) to mean to give way to faster cars. It also has two further meanings where the driver is about to be overtaken or a particular car is about to be lapped. The flag is also used to signal that the track or a section of the track is either wet or starting to become wet.
Usually, it appears in FIA-sanctioned championships although very rarely these days if at all. It does not appear in IndyCar, NASCAR, or iRacing.
FIA-sanctioned championships: Driver About To Be Overtaken, Driver Leaving The Pits If Traffic Is Approaching On The Track, Give Way To Faster Cars, Car About To Be Lapped, Allow The Following Car To Pass At The Earliest Opportunity, Track is Wet, Section of Track is Wet.