wixData.query include() return undefined

I have tried to get an array of tag’s labels in Posts Collection of Blog Collection.

import wixData from 'wix-data';

$w.onReady(function () {

        .then((results) => {
            results.items.forEach((r) => {
                let item = r.tags.label; // PROBLEM IS HERE
        .catch( (error) => {
        let errorMsg = error.message;
        let code = error.code;
    } );

When it only r.tags:
It show the array of tag object (Pretty good)

But when I want to call the label r.tags.label:
It show the list of undefined

Please help! Thanks you all!