I want to create a dynamic link with user_id using branch link api in braze. The link is being created, but it's falling to the app, not the fallback url I want. What's wrong with that?

{% connected_content https://api.branch.io/v1/url
 :method post
 :headers {"Content-type": "application/json"}
 :body branch_key=(mykey)&$fallback_url=(web link) &$web_only=true&channel=crm&campaign={{${user_id}}}
 :content_type application/json
 :save payload %}{{payload.url}}