Hey there Buddy,
Hope you’re doin great!
The way to add the customScopeKey is quite simple. The express-jwt-authz accepts the two arguments. The first argument would be the permissions and second argument would be options object. Something like this
const checkScope = jwtAuthz(["read:messages"], {"customScopeKey" : "permissions" })
For more info about the express-jwt-authz, you could go ahead and check out the npm package here