First, you're on an out of date version. The current version is 16.6.
How are you returning the call? When I return a call by tapping on the number in Recents it always uses the method that the call I am returning used.
Also, this is a user-to-user forum with minimal Apple participation. If you want to communicate with Apple here is some guidance:
Apple’s formal support can be reached several ways:
- You can provide feedback to Apple at→ Product Feedback - Apple where your issue or suggestion will be recorded, but you will not get a reply
Note that both of the above have options to receive a callback or chat
About the only communications method not used by Apple support is inbound email, probably because the volume would be overwhelming, and separating the wheat from the chaff (or, to us engineers, a poor signal to noise ratio) would be almost impossible.