I would classify that as access to production systems.
The other access rights that come from staff access is either incedential or miss /debt in architecture.
The leak includes source code of multiple active websites and applications that are operated under the umbrella of Twitch/Amazon.
Why would an intern have access to this data?
If you're saying that Twitch runs their developer environment in a lousy manner (and you have proof of this), then please go ahead.
But to imply that an intern/average developer would be given access to all this branching information is ignorant.
monorepos are a thing at several companies (e.g. Google).
