We are unable to fix this, unfortunately.
This is a change Apple made in watchOS 8.1, to always default text entry to the non-dictation option (on Series 7, that is the new keyboard, on previous models the “scribble” handwriting input).
There is no way for developers to override this behavior, and the watch does not remember your preference for the last used mode (it did on watchOS 8.0, but Apple eliminated that behavior on 8.1). This change not only affects Drafts, but anyplace you do text input on the watch (message replies, etc.).
I highly recommend you report this as a bug/regression to Apple using the Feedback Assistant. I have been trying to draw attention to this change because I think it is a significant regression for most watch users. I report it as a bug during the beta cycle but was informed by Apple it was an “intentional change”. Maybe enough feedback from users will make them reconsider.