Why does System.Text.Json.Serialization.JsonSerializer encode double-quotes instead of merely escaping them?

Question

I am wracking my brain about this and can't figure out why or how to fix it.

This test should pass:

[Test]
public void EncodingTest()
{
    var json = JsonSerializer.Serialize("\"");

    Assert.AreEqual("\\\"", json);
}

but it doesn't. It's saying that a double-quote " in a string should be translated to \", which is (fairly universally) the preferred serialization for this character. (See string at json.org.)

But what's actually happening is that it gets encoded as \u0022 which is the unicode code-point for it.

I understand that \u0022 is allowed, but it's horribly unreadable.

I've found this question which pointed me to

• GH issue dotnet/runtime #29879
• GH issue dotnet/runtime #29374
• GH PR dotnet/corefx 39524 which includes a test case to explicitly ensure it encodes this way.

None of what I've read says how to get the JsonSerializer to just escape it (like every other serializer I've seen).