SvelteKit is wrapping my response and I can't figure out why [duplicate]

I have a SvelteKit action that looks like this:

export const actions = {    upload: async ({request}) => {        // some logic        return { success: true };    }}

However, when I call this endpoint the response returned looks like this according to my browser's network tab:

{"type":"success","status":200,"data":"[{\"success\":1},true]"}

I tried:

• default action vs named action
• no middlewares set up