Meta always sent as 'on' for true

Uppy
1

Using the following code example

const uppy = Uppy.Core({ /* ... */ });
uppy.use(XHRUpload, {
  endpoint: /* ... */,
  fieldName: 'file',
  formData: true,
  bundle: false,
});

const myValue = true;
uppy.setMeta({ myValue });

If myValue is true or "true" it’s always sent as

Content-Disposition: form-data; name="myValue"

on

Why is it like this and can this be disabled?