Haven't had that since the old FLYSURFER bags... I used a dry lube like a silicon spray to lightly coat them. Seemed to work...
Lanolin spray seems to work pretty well, but better solution is to have all-plastic zippers or no zippers at all. Dunno why some manufacturers use metal zippers on kite bags
I've got all plastic slider zippers. Zero problems with them. I had a couple of board bags with metal sliders and bought new zips and sewed them in. Pretty easy job and the bags and zips work like new.
About the only thing I found that worked with metal zips is to use them frequently. I only got corrosion on zips that had not been used for weeks/months. Since I started foiling that means my surfboard bags with metal zips. If they did get corroded then soaking the slider in boiling water freed them up. I've used spray on silicone lube. It didn't make much of a difference.
My wingding board came with a bag with metal sliders. Apparently YKK now have metal sliders designed for marine use (boat covers and clears and stuff). Hopefully the new bag has those sliders.
You can't just replace the metal sliders on zips with plastic sliders. Most board bags use coil zips and you can't get plastic sliders for coil zips. The other kind with the teeth are called Vislon zippers and you can get plastic sliders for them.
2 out of 2 of my last Ozone kite bags (2020 models with plastic zips) buggered up within 12-18 months of use. Not 'stuck' but you know when they come apart mid-way down a fully zipped section and then you have to go back and forth with the zip to get it done back up but then it busts open again and spills everything out and generally makes life hell for you? Yeah so had them 'replaced' for free under warranty, with generic Ozone bags, which touch wood have been OK so far.
Using the zip regularly seems to be the only thing I've seen that works. Had some bags that I've been using for 4 years without a problem. No kiting for months in the first lockdown and suddenly gummed up.
So - get out and kite more. Will save you money in the long run