How to add new authorization scopes to an existing app

[yudai-nkt]

Plan: Premium
Country: Japan
Device: N/A
Operating System: N/A

I developed an app with Spotify web API a while ago and it only had the user-follow-read scope. Now I need the playlist-modify-public scope to implement a new feature. Below is the HTTP request I made with curl:

curl -v -G -d client_id=$CLIENT_ID_OF_THE_AFOREMENTIONED_APP -d redirect_uri=https://github.com/yudai-nkt/sbotify -d response_type=code -d scope="user-follow-read%20playlist-modify-public" https://accounts.spotify.com/authorize

However, this does not ask me to authorize the access, so I cannot get a new authorization code that permits both scopes (and the subsequent access token and refresh token).

What am I missing here? How can I add a new authorization scope to an existing app?