Is there an EKS Auto Mode-specific page that describes:

• which add-ons are provided as "default"
• which are "self-managed"
• some third option?

I found mention of Auto Mode here but nothing to say what's default on which platform.

The column, Compatible compute types confirms compatibility; I would't infer from compatibility that it's cluster default.

The Considerations for Amazon EKS Auto Mode confirms what is default on the cluster with odd phrasing

With Auto mode compute, many commonly used EKS add-ons become redundant, such as:...

Specifically, one page suggests that the vpc-cni plugin is "redundant", while the other says that is compatible with EC2. That's a bit confusing.

Recommendation: one, simple table with a few columns:

etc