Google Picker API Invalid origin value error

Today Google Picker stopped working in my Google Sheets add-on without any changes to the code. The error in the modal dialogue reads:

Invalid origin value.

The errors in console are:

Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('https://docs.google.com') does not match the recipient window's origin ('https://n-a6p4dqsl***d6wq-0lu-script.googleusercontent.com')

dropping postMessage.. was from unexpected window

dropping postMessage.. was from unexpected window

Invalid 'X-Frame-Options' header encountered when loading 'https://docs.google.com/picker?protocol=gadgets&origin=https%3A%2F%2Fdocs.google.com%2F&sdr=true&title&oauth_token=<oathToken>&developerKey=<developerKey>&hostId=n-a6p4dq***d6wq-0lu-script.googleusercontent.com&relayUrl=https%3A%2F%2Fn-a6p4dq***d6wq-0lu-script.googleusercontent.com%2Ffavicon.ico&nav=((%22documents%22%2Cnull%2C%7B%22selectFolder%22%3Atrue%2C%22parent%22%3A%22root%22%7D)%2C(%22documents%22%2Cnull%2C%7B%22dr%22%3Atrue%2C%22includeFolders%22%3Atrue%7D))&rpcService=qhurmoc5w4l7&rpctoken=xssf8g42xc2&thirdParty=true#rpctoken=xssf8g42xc2': 'ALLOW-FROM https://docs.google.com/' is not a recognized directive. The header will be ignored.

It maybe that the error is linked to this line of code where I do setOrigin():

        var picker = new google.picker.PickerBuilder()
            .addView(driveView)
            .addView(drivesView)
            .hideTitleBar()
            .setOAuthToken(token)
            .setDeveloperKey(DEVELOPER_KEY)
            .setCallback(pickerCallback)
        --> .setOrigin(google.script.host.origin)
            .setSize(DIALOG_DIMENSIONS.width - 2,
                DIALOG_DIMENSIONS.height - 2)
            .build();

But this line is directly from the documentation of the Google Picker API and worked properly before. If I change google.script.host.origin, that returns https://docs.google.com as url to https://n-a6p4dqsl***6wcd6wq-0lu-script.googleusercontent.com, I get the same error and a new one, so that is not it.

I also cannot add this as as an authorized javascript origin in the GCP project as it returns the following error:

Invalid Origin: uses a forbidden domain

(This has been the case of a while)

This seems like a new error and I wasn't able to find an answer neither on Google's issues tracker nor on StackOverflow.

Anyone facing this as well or have an idea how it can be handled?

Putting an end, the only way to solve this is to remove the trailing slash after

From

docs.google.com/

To

docs.google.com

Contrary,

The google.script.host.orgin gives the "https://docs.google.com/" which causes the error. Hence you need to hard code as

"https://docs.google.com"

Google has made some changes recently which might have bubbled this issue.

UPDATE

You can use this function - and call - ...... setOrigin(getOrigin())

function getOrigin() {
    var url = google.script.host.origin;
    return url.substr(url.length - 1) === "/" ? url.substr(0, url.length - 1) : url;
}