Error TS4020 or TS4023, working with mixins, base class has static symbol property, only when multiple files.

Bug Report

In the following code (file: index.ts)

export class TestComponent extends MixinComponent(Component<HTMLElement>)<number> {
}

I get error TS4020: 'extends' clause of exported class 'TestComponent' has or is using private name 'Test'.

I've gotten that error before and managed to fix it by exporting the "private name" the compiler is complaining about.

But in this case, said name IS being exported (file: component.decl.ts)

export const Test = Symbol("test");  // <--- HERE

export declare abstract class Component<T extends HTMLElement = HTMLElement> {
  readonly element: T;

  public static [Test]: string;
}

What other reason is there to cause this error? I don't see no "private name".

It's also a different error Exported variable 'MixinParent' has or is using name 'Test' from external module "/sandbox/component.decl" but cannot be named. if I put the inheritance in two separate lines (file: index.ts)

export const MixinParent = MixinComponent(Component<HTMLElement>);

export class AnotherTestComponent extends MixinParent<string> {
}

🔎 Search Terms

all in title.

🕗 Version & Regression Information

latest.
(declaration: true)

⏯ Playground Link

codesandbox.io link

in playground is not reproducible, I suppose because everything is in a single file, but here's a link anyway.

Playground link

💻 Code

above.

🙁 Actual behavior

errors.

🙂 Expected behavior

no errors.