A token doesn’t last forever
So if the website is using a token it must be self regenerating the app access token to use it.
You really need to talk to this guy, or get someone who can go thru your codebase and sort it all out. Since you are fighting to learn the Twitch API, and upgrade from webhooks to eventsub and the “mess” you have inherited from this person.
Only setup the subscriptions to the topics you need.
Your original code is for follows
And I cite information about the subscribers topic to help you understand the duality of access tokens with EventSub.
So if you don’t need subscriber/other private data, don’t request/set up those subscriptions to those topics.