WebdriverIO get cookies method doesn't work

Question

I'm setting a cookie as it is on WDIO page, and then want to show them in the console:

await browser.setCookies([
        {name: 'CTSESSION', value: 'AAAAA33jg$ddsAvV54jg9'}
    ])
const testCookie = await browser.getCookies(['CTSESSION'])
console.log(testCookie);

but instead of my cookie I'm getting:

[object Object]

The same I'm getting when I do

const testCookie = await browser.getAllCookies()
console.log(testCookie);

then in a response I've got:

[object Object],[object Object],[object Object]

Can anyone advice why I don't get values?