EventSub : subscription missing proper authorization

[BarryCarlyon]

You need to user authenticate to get permissions for your ClientID

And THEN use the App Access Token with EventSub.
EventSub only supports App Access Tokens.

@BarryCarlyon

So: obtain a User Access Token with the relevant scopes via a normal oAuth (the discard it or keep it, I usually keep it so I can do “my service was down” catch ups and resyncs)
Then use your App Access Token (no user attached) to create the subscriptions