Global errors differ depending on initial state of playground

I'm having a hard time consistently reproing this, so bare with me.

First, use es2020 as a target.

Playground for this example:

function foo() {
    await using asd = 123;
}

Playground for this example:

function foo() {
    //await using asd = 123;
}

In both cases, toggle a comment on the line in foo, and then toggle the comment state again.

Depending on the initial contents of the playground, the following errors will not reappear:

Cannot find global type 'AsyncDisposable'.(2318)
Cannot find global type 'Disposable'.(2318)

What's more, if you try applying a quick fix on the await keyword to add the async keyword to the function you may get different results than if you enter it manually.

Start with the two linked Playground examples using the es2020 target, then reproduce the comment toggling sequence in foo. Compare whether the AsyncDisposable and Disposable diagnostics and the await quick-fix remain consistent after each toggle; done means both initial states produce the same errors and quick-fix result.