There are spray cans of repellent but not sure they work. Have you considered replacing with copper lines? Or putting the lines inside some hard plastic or light metal piping?
My choice would be to switch to braided stainless steel propane lines.
Call your local LP company that offers delivery. Many of them have expertise in making propane lines and could either help you or find a source for stainless lines made up with end fittings installed.
2017 SLX 195RB
2021 Jeep Grand Cherokee Summit L 5.7L V8
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