Jet fuel does not use lead. I'm also pretty sure jet fuel never used lead; it has no reason to (jet engines are not particularly picky about what they burn-- jet fuel is basically kerosene).

Aviation gasoline does use lead-- it's used there to prevent predetonation (engine knock), which is bad for a car engine but really bad in something that's supposed to be keeping you in the air. Replacing it is an ongoing effort, but it's taking a while-- largely because of certification requirements, because it's pretty important to make sure that your new gasoline formulation isn't going to, again, make that thing that's keeping you in the air fail. And there are a lot of older GA airplanes out there that would need recertification for a new fuel.

Jet fuel has no lead, it's basically kerosene. Avgas for reciprocating engines (basically only small general aviation planes/helicopters) currently contains lead but is moving to be lead free in the US.

Jet fuel isn't leaded. It’s piston engine general aviation aircraft that use leaded gas.