I faced the same issue.
For me, I guess reason is cordova.plugins.diagnostic .
But I don't use bluetooth functions of this plugin.
Have no idea how to deal with it.
This is a recurring issue. How did you guys get around it? Did you just make up some "excuse" description for it or did Apple accept the explanation that you don't really invoke these?
I'm facing the same problem and found this other question (https://forums.developer.apple.com/message/308163#308163) where somenone else is also asking for a way to proactively tell what usage descriptions any third party libraries may need before it gets submitted. I've also asked this question in StackOverflow (https://stackoverflow.com/q/53710674/4124574). No clear answer yet.