Something to do with being unable to make the fuel tanks inert. If you Google it there's quite a lot about it. I'm no expert so I can't tell you what that really means
https://www.forbes.com/sites/erictegler/2022/11/23/air-force-f-35-lightning-iis-still-cant-fly-within-25-miles-of-lightning/?sh=7659da1e663e dated 2022, but covers the issue in detail.
Something to do with being unable to make the fuel tanks inert. If you Google it there's quite a lot about it. I'm no expert so I can't tell you what that really means
https://www.forbes.com/sites/erictegler/2022/11/23/air-force-f-35-lightning-iis-still-cant-fly-within-25-miles-of-lightning/?sh=7659da1e663e dated 2022, but covers the issue in detail.