Who Me Too'd this topic

I've been using the Spotify API using Spotipy for some time. That stopped working for me a few weeks ago - the server isn't able to get an oauth2 token using https://accounts.spotify.com/api/token / grant_type=authorization_code anymore.

The error returned is some HTML document including "403. That’s an error. Your client does not have permission to get URL /api/token from this server. That’s all we know."

I've been testing getting auth tokens using cURL. The exact same request fails when sent from that server but gets processed correctly when sent from another IP.

What's going on? I'm fairly sure I've not been hammering the Spotify API with requests - how can I review/debug the situation and get the server IP unblocked?