Can state also be removed? I assume we can get it from instance.

Would you mind elaborating more on getting state from instance? Just want to make sure I get it right.

(Edited)
So I currently pass in instance and removed both state and visibleColumns since these can be derived from instance.

Since instance is a Table-wide concept, I think we can store it in context.

I see there is a TableColumnsContext that stores instance.columns. We can rename this to TableInstanceContext and store instance instead.

One thing that we'll need to verify is whether instance is a stable/memoized object, i.e. it doesn't change on every re-render.

Can columnRefs be removed? It doesn't feel quite right for a ColumnHeader to mutate its parent component's variables.

I have removed this prop.

You have removed the whole functionality, not just the prop. What I was asking for is to move the columnRefs-related code from ColumnHeader into Table.

You can pass a ref from the outside.

ref={(el) => {
  if (el) {
    columnRefs.current[column.id] = el;
  }
}}

And the refs will need to be merged inside ColumnHeader.