Looks like Apple fixed this with iOS 14 Beta 6!
Same code as above just works now!
On the server side (I am using node.js) now cbor.decodeAllSync returns "apple" as fmt before this was "none"
let ctapMakeCredResp = cbor.decodeAllSync(attestationBuffer)[0]
console.log('fmt',ctapMakeCredResp.fmt) // will return "apple", before iOS 14 BETA 6 this was "none"