Embed HTTP POST error 403 on Google Chrome 88

[carlosnasillo]

This issue only seems to occur with Google Chrome ~88.

The embed frame opens fine and displays the preview image of the video. but on pressing play the following is logged to console.

POST https://www.youtube.com/youtubei/v1/player?key=<XXXX> 403 - base.js:8135

This is the current init

<script>
    $(".js-modal-btn").modalVideo({
        channel: 'youtube',
        youtube: {
            origin: "https://example.com",
            enablejsapi: 1,
            wmode: 'transparent',
        }
    });
</script>

Disabled adblockers, etc nothing seems to fix it. Interestingly enough it works fine on Safari and Firefox. Any ideas?